Sensor device for interrupting irrigation

ABSTRACT

Methods and apparatus are provided herein for permitting or interrupting irrigation using sensor equipment. In one embodiment, a method for controlling irrigation comprising the steps of: generating an indication representing the amount of rain fall at a sensor unit; transmitting a signal comprising at least the indication from the sensor unit to an interface unit, wherein the interface unit is adapted to cause an interruption of programmed watering schedules of an irrigation controller; receiving the signal at the interface unit; determining, based at least on the indication from the signal, whether irrigation should be interrupted; and generating an interrupt command to interrupt irrigation.

This application is a continuation of U.S. application Ser. No.11/766,092, filed Jun. 20, 2007, entitled SENSOR DEVICE FOR INTERRUPTINGIRRIGATION, which claims the benefit of U.S. Provisional Application No.60/866,595, filed Nov. 20, 2006, entitled WIRELESS SENSOR FORINTERRUPTING IRRIGATION and U.S. Provisional Application No. 60/805,331,filed Jun. 20, 2006, entitled RAIN SENSOR DEVICE AND METHOD FORINTERRUPTING WATERING OF AN IRRIGATION CONTROLLER, all of which areincorporated in their entirety herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to the controlling of theexecution of a watering program by an irrigation controller.

2. Discussion of the Related Art

Rain sensors for use in the interruption of programmed wateringschedules of an irrigation controller are generally known to include amaterial that is responsive to rain, and in the event a preset level ofrain is exceeded, a switch is activated which outputs a signal to theirrigation controller that causes the controller to cease the executionof watering schedules.

U.S. Pat. No. 6,452,499 to Runge et al. (which is incorporated herein byreference) describes a wireless rain sensor that uses a hygroscopicmaterial that expands when exposed to water. When the hygroscopicmaterial expands beyond a specified point or threshold, an integratedtransmitter wirelessly transmits a radio frequency signal to a receiverattached to the controller. The receiver receives the wireless signaland causes the controller to cease watering. Similarly, U.S. Pat. No.6,977,351 to Woytowitz (which is incorporated herein by reference)describes a wireless rain sensor including a hygroscopic material thatis not mechanically connected to the switch that triggers thetransmission of the wireless signal that will cause the interruption ofwatering The threshold level may be adjusted by a user through themechanical adjustment of the distance the hygroscopic material mustexpand before actuating the switch, such as described in U.S. Pat. No.6,570,109 to Klinefelter et al (which is incorporated herein byreference). Thus, in order to exceed a selectable threshold, thehygroscopic material must expand a selectable distance, whichcorresponds to a selectable level of rain fall.

SUMMARY OF THE INVENTION

Several embodiments of the invention provide methods and apparatus forpermitting or interrupting irrigation using sensor equipment.

In one embodiment, the invention can be characterized as a method forcontrolling irrigation comprising the steps of: generating an indicationrepresenting the amount of rain fall at a sensor unit; transmitting asignal comprising at least the indication from the sensor unit to aninterface unit, wherein the interface unit is adapted to cause aninterruption of programmed watering schedules of an irrigationcontroller; receiving the signal at the interface unit; determining,based at least on the indication from the signal, whether irrigationshould be interrupted; and generating an interrupt command to interruptirrigation.

In another embodiment, the invention can be characterized as a devicefor controlling irrigation comprising an interface unit. The interfaceunit comprises an input unit adapted to receive a signal from a sensorunit, the signal comprising an indication representing an amount of rainfall at the sensor unit. The interface unit also comprises a controllercoupled to the input unit adapted to process the signal to determinebased at least on the indication from the signal, whether irrigationexecuted by an irrigation controller should be interrupted and togenerate an interrupt command to cause the interruption of theirrigation.

In a further embodiment, the invention may be characterized as a rainsensor comprising: a moisture absorptive material adapted to move inresponse to rain fall; a plunger adapted to move in response to andproportional to the movement of the moisture absorptive material; and asensor element. The sensor element comprises a first element and asecond element coupled to the plunger and adapted to move with theplunger relative to the first element causing a change in a variablecorresponding to the amount of rain. The rain sensor also comprises acontroller adapted to measure the variable and further adapted togenerate a signal comprising an indication of the amount of rain fallbased on the variable.

In yet another embodiment, the invention may be characterized as amethod for wireless installation of an irrigation control devicecomprising the steps of: locating a first wireless unit at a firstlocation; establishing a wireless path of communication between thefirst wireless unit and a second wireless unit remote from the firstlocation; moving the second wireless unit to a plurality of possibleinstallation locations, wherein the signal strength changes as thesecond wireless unit is moved; automatically determining the signalstrength as the second wireless unit is moved; automatically displayingthe signal strength at the second wireless unit as the second wirelessunit is moved; and determining which of the plurality of possibleinstallation locations to fix the second wireless unit based on thedisplayed signal strength.

In a further embodiment, the invention may be characterized as a devicefor controlling irrigation comprising a sensor unit adapted to sense anamount of rain fall; a two-way communication link coupling the sensorunit to an interface unit; and the interface unit adapted to receiveinformation corresponding to the amount of rain fall via the two-waycommunication link from the sensor unit. The interface unit is furtheradapted to cause an interruption of irrigation executed by an irrigationcontroller based at least in part on the information from the sensorunit.

In another embodiment, the invention may be characterized as a methodfor controlling irrigation comprising the steps: sensing an amount ofrain fall at a sensor unit; communicating information corresponding tothe amount of rain fall from the sensor unit via a two-way communicationlink to an interface unit; and causing, at the interface unit, aninterruption of irrigation executed by an irrigation controller based atleast in part on the information from the sensor unit, the interfaceunit being adapted to communicate with the sensor unit via the two-waycommunication link.

In yet another embodiment, the invention may be characterized as amethod for controlling irrigation comprising the steps of: generating anindication representing the amount of rain fall at a sensor unit;transmitting a signal comprising at least the indication from the sensorunit to an interface unit, wherein the interface unit is adapted tocause an interruption of programmed watering schedules of an irrigationcontroller and wherein the interface unit is separate from theirrigation controller; receiving the signal at the interface unit;receiving user input relating to the interruption of the programmedwatering schedules of the irrigation controller via a user interfaceintegrated with the interface unit, wherein the user input defines arain interruption threshold; determining, at the interface unit, basedat least on the indication from the signal and the user input, whetherirrigation should be interrupted; and generating an interrupt command tointerrupt irrigation in the event it is determined that the irrigationshould be interrupted.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of severalembodiments of the present invention will be more apparent from thefollowing more particular description thereof, presented in conjunctionwith the following drawings.

FIG. 1 is a diagram of a rain sensor device for interrupting executionof one or more watering schedules of an irrigation controller accordingto several embodiments.

FIG. 2 is a variation of the rain sensor device of FIG. 1 according toseveral embodiments.

FIG. 3 is a functional diagram of the components of some embodiments ofa rain sensor unit of the rain sensor device of FIGS. 1 and/or 2.

FIG. 4 is a functional diagram of the components of some embodiments ofan interface unit of the rain sensor device of FIGS. 1 and/or 2.

FIG. 5 depicts a simplified flow diagram of a process for use inadjusting the mode of operation of the sensor unit of FIG. 3.

FIG. 6 depicts a simplified flow diagram of a process for use indetecting and inhibiting an irrigation cycle in accordance with oneembodiment.

FIG. 7A is one embodiment of the interface unit of the rain sensordevice of FIG. 4 illustrating user inputs and display outputs.

FIG. 7B is another embodiment of the interface unit of the rain sensordevice of FIG. 4 illustrating user inputs and display outputs.

FIG. 8 is another embodiment of the interface unit of the rain sensordevice of FIG. 4 illustrating user inputs and display outputs.

FIG. 9 depicts a simplified flow diagram of a process for use ininitializing the rain sensor device illustrated in FIGS. 1 and 2.

FIG. 10 illustrates a simplified flow diagram of a process for use inthe event that loss of communication occurs between the sensor unit andinterface unit of rain sensor device or system illustrated in FIGS. 1and 2.

FIGS. 11-19, 27A-B and 28 illustrate various embodiments of thecomponents of a rain sensor unit for use with a receiver unit forinterrupting execution of one or more watering schedules of anirrigation controller according to several embodiments.

FIGS. 20 and 21 graphically illustrate signal strength profiles used toapproximate the propagation environment over communication distancesless than the breakpoint distance at 915 MHz and 868 MHz, respectivelyaccording to one embodiment.

FIG. 22 illustrates an example implementation of a “TEST” operationalmode utilized during the installation of the sensor unit in accordancewith one embodiment.

FIG. 23 illustrates a simplified flow diagram of an exampleimplementation of a sleep or normal operational mode at the sensor unitof FIGS. 1 and 2, according to some embodiments.

FIG. 24 illustrates a simplified flow diagram of a process for use indetecting and inhibiting an irrigation cycle in accordance with oneembodiment.

FIG. 25 illustrates a simplified diagram of one implementation of thelow temperature operational mode according to some embodiments.

FIG. 26 illustrates one implementation of a “TEST” operational mode inaccordance with some embodiments.

FIG. 29A is another embodiment of the interface unit of the rain sensordevice of FIG. 4 illustrating user inputs and display outputs.

FIG. 29B is another embodiment of the interface unit of the rain sensordevice of FIG. 4 illustrating user inputs and display outputs.

FIG. 30 graphically illustrates example rain profiles and the points atwhich irrigation is interrupted or reactivated based on a rate of changeof a sensed amount of rain fall, according to some embodiments.

FIG. 31 illustrates a simplified flow diagram of one embodiment of theoverall operation of the rain sensor system 10.

FIG. 32 illustrates a simplified flow diagram of one embodiment of aprocess for installing and pairing the interface unit and the sensorunit of FIGS. 1 and 2 together.

FIG. 33 illustrates an exemplary embodiment of a modular irrigationcontroller having an interface unit module.

FIG. 34 illustrates a rain sensor system in which an interface unit ispaired and communicates with n sensor units 12 a-n according to someembodiments.

FIG. 35 illustrates a rain sensor system in which a sensor unit ispaired with and communicates with n interface units 14 a-n according tosome embodiments.

Corresponding reference characters indicate corresponding componentsthroughout the several views of the drawings. Skilled artisans willappreciate that elements in the figures are illustrated for simplicityand clarity and have not necessarily been drawn to scale. For example,the dimensions of some of the elements in the figures may be exaggeratedrelative to other elements to help to improve understanding of variousembodiments of the present invention. Also, common but well-understoodelements that are useful or necessary in a commercially feasibleembodiment are often not depicted in order to facilitate a lessobstructed view of these various embodiments of the present invention.

DETAILED DESCRIPTION

The following description is not to be taken in a limiting sense, but ismade merely for the purpose of describing the general principles ofexemplary embodiments. The scope of the invention should be determinedwith reference to the claims.

Referring first to FIG. 1, a diagram is shown of a rain sensor system 10for interrupting execution of one or more watering schedules of anirrigation controller 30 according to several embodiments. The rainsensor system 10 includes a sensor unit 12 having a first input/outputunit 16 and an interface unit or system 14 having a second input/outputunit 18. The first input/output unit 16 and the second input/output unit18 are coupled to each other by a communication link 15. The interfaceunit 14 is coupled to an irrigation controller 30 (either directly tothe controller via an interface 38, e.g., a rain sensor input, orindirectly, e.g., coupled to the controller output lines 32 or a commonline 34, as illustrated in dashed lines). Alternatively, in someembodiments, the interface unit may be implemented as a part of theirrigation controller. For example, in one embodiment, the interfaceunit may be implemented as a module that may be inserted into a modularirrigation controller. The irrigation controller 30 is programmed toexecute one or more watering schedules. In one form, the irrigationcontroller 30 may output activation signals (e.g., 24 volt powersignals) to respective ones of a plurality of activation lines 32, eachcoupled to a valve located in the region to be irrigated, an electricalswitch to activate or deactivate lighting or other devices controlled bythe controller 30. As is well known, one or more sprinkler devices, driplines and/or other irrigation devices may be coupled to each valve.

The sensor unit 12 is typically located remotely from the interface unit14 in a position where it is exposed to rainfall. For example, thesensor unit 12 may be mounted to a rooftop, light pole, or telephonepole. In some embodiments the sensor unit 12 periodically obtainsmeasurements of parameters such as amount of rain fall, and/orprecipitation, temperature, and/or other parameters, and transmits theinformation to the interface unit 14. The interface unit 14 receives thedata from the sensor unit and processes it to determine whether toinhibit or interrupt irrigation. Additionally or alternatively, in someembodiments, the sensor unit may initiate transmission to the interfaceunit 14 once it detects a change in some atmospheric parameters, e.g.,amount of rain fall and/or temperature, and sends an update message tothe interface unit. In one embodiment, the message may include theamount of rain fall, temperature, battery strength, signal strengthand/or other data available at the sensor unit.

In some embodiments, once the interface unit 14 detects the beginning ofan irrigation cycle, it is instructed and/or is activated to communicatewith the sensor unit 12 to request information regarding measurementparameters, such as but not limited to precipitation data, temperatureand/or other such parameters. In one embodiment, the sensor unit 12receives the request, obtains the requested measurement data andtransmits the information to the interface unit 14. In someimplementations, the interface unit 14 receives instructions from theirrigation controller 30 requesting the interface unit 14 to transmit arequest to the sensor unit 12 requesting the measurement data.

In some embodiments, the interface unit 14 is located remotely from thesensor unit 12 and proximate to the irrigation controller 30 in alocation that is, in some implementations, accessible to the user. Theinterface unit is also coupled to the irrigation controller 30 (eitherdirectly or indirectly). In some embodiments the interface unit may beimplemented as a part of the irrigation controller and located on theirrigation controller. In one embodiment, for example, the interfaceunit may be implemented as a module that may be inserted into a modularirrigation controller.

In some embodiments, each interface unit 14 is specifically paired to asensor unit so that each rain sensor system 10 includes a paired sensorunit 12 and interface unit 14. Alternatively, in some embodiments eachinterface unit 14 is paired to more than one sensor unit 12. In theseembodiments, each sensor unit 12 is paired with the interface unitindependently. FIG. 34 illustrates a rain sensor system 10 in which theinterface unit 14 is capable of pairing and communicating with n sensorunits 12 a-n via communication links 15 a-15 n. Additionally, in one ormore embodiments, each sensor unit 12 is paired with more than oneinterface unit 14, wherein, the sensor unit is paired with each ofindividual interface unit 14 of the plurality of interface units. FIG.35 illustrates a system 10 in which the sensor unit 12 is capable ofpairing with and communicating with n interface units 14 a-n viacommunication links 15 a-15 n. The pairing may be implemented at thetime of purchase, at the time of installation, during batteryreplacement, or at other such times before the system beginsfunctioning.

The interface unit and sensor unit may be paired together using severaldifferent methods. For example, in one embodiment, the sensor unit 12and the interface unit 14 may be paired using a wired serial interface,e.g., the I2C (Inter Integrated Circuit bus) interface and protocol. Thepairing may be implemented using an additional 3 pin header connector(not shown) on both the sensor unit 12, and the interface unit 14, and ashort 3-wire cable (not shown) with matching receptacle connectors onboth ends, and a firmware procedure for executing the pairing uponconnecting both units together. This method of pairing the two unitsdiminishes problems created by side radio transmissions whenimplementing the pairing. Alternatively, the interface unit and thesensor unit may be paired by invoking a special mode of operation of theinterface unit 14, in which the ID information regarding the sensorunit's radio signal may be memorized and used for matching with the samesensor unit 12 in the future.

In another embodiment, pairing is implemented by temporarily positioningthe sensor unit 12 and the interface unit 14 close together and puttingthe sensor unit 12 in a high (preferably highest) power-transmissionmode with packets following each other without any gap between them andhaving a special pairing-mode identification bit, while the interfaceunit 14 is held in a low (preferably lowest) sensitivity mode. The closeproximity between the sensor unit 12 and the interface unit 14, combinedwith high-power transmissions from sensor unit and low-sensitivity ofthe interface unit help to eliminate any interfering emissions. Thechance of catching a side emission may be further diminished by using aspecific identifier for pairing mode, which helps eliminate any regulartransmission from other sensor units.

FIG. 32 illustrates one possible implementation of a process 3200 ofinstalling and pairing the interface unit 14 and the sensor unit 12together. At step 3210 the interface unit initiates a set up request andtransmits the request. The sensor unit 12 receives the request, in step3212, and continues to step 3214 where it determines whether or notcertain criteria are met. For example, the request message may compriseinformation about the interface unit 14. In one embodiment, the sensorunit 12 may use this information in step 3214 to determine whether it isable to pair up with the interface unit 14. For example, in someembodiments, the user may exert a manual force on a part of the sensorwherein the force fully depresses the plunger, the sensor unit willquery the rain sensor 318 and will use the measurement to determinewhether the plunger in the rain sensor 318 is fully depressed todetermine whether there is user authorization to pair up with aninterface unit.

Once the sensor unit determines that it is ready to pair up with theinterface unit, it will generate and send or transmit an acknowledgmentmessage to the interface unit in step 3216. The message may compriseidentification information about the sensor unit, and/or other datastored in memory of the sensor unit and/or available from the sensorsand or other devices coupled to the sensor unit 12. Additionally, instep 3216, the sensor unit may store information about the interfaceunit 14, for example, information received in the request message intoits memory. In step 3218, the interface unit then receives theacknowledge message, and pairs up with the sensor unit. For example, theinterface unit may store information about the sensor unit, received inthe acknowledge message and/or other available sources, into its memory.Additionally or alternatively, when performing step 3214, the sensorunit may also determine whether it is ready for set up by ensuring thata user input, e.g. authorization, has been entered.

Referring generally back to FIG. 1, the interface unit 14 receivesmeasurement data from the sensor unit 12 and processes this data todetermine if irrigation (such as programmed into an irrigationcontroller 30) should be permitted or interrupted. For example, in oneembodiment, the interface unit 14 determines whether a predeterminedrelationship exists between the received measurements detected and astored preset level or threshold and/or other criteria. For example, theinterface unit may determine if the signal indicative of an amount ofrain has exceeded a threshold level of rainfall, and/or whether arelationship exists between the signal and some criteria. For example,in one embodiment, the interface unit may use the informationtransmitted from the sensor unit 12 to determine a rate of change, forexample, for the rain fall accumulation, and determine whether the rateof change satisfies a predetermined relationship.

Additionally or alternatively, the interface unit may look at therelationship between the received measurements when processing the datato determine whether irrigation should be inhibited or interrupted. Forexample in one embodiment the interface unit receives the measurementsand analyzes the relationship between one or more of the amount ofrainfall, the rate of rain fall and the temperature. Alternatively insome instances, the information may be processed by the sensor unit 12,where the determination regarding the relationship may be made by thesensor unit, and the determination may then be transmitted to theinterface unit 14 by the sensor unit 12, e.g., in response to therequest from the interface unit 14. If the predetermined relationshipexists (e.g., the threshold level of rainfall has been exceeded by theamount of sensed or measured rain fall), the electronics of theinterface unit 14 and/or the controller 30 generate the appropriatesignaling to cause the interruption of the execution of wateringschedules by the irrigation controller 30.

This approach to overriding or interrupting watering based on measureddata, such as sensed rain fall amounts is fundamentally different thanthe approach of known rain sensor devices that interrupt controlleroperation when a threshold level of rain has been exceeded. That is,traditional rain sensors, such as described in U.S. Pat. No. 6,452,499to Runge et al., and U.S. Pat. No. 6,977,351 to Woytowitz (both of whichare incorporated herein by reference), employ a remote rain sensor thatsends a signal to its receiver to indicate that the rain threshold hasbeen exceeded, where the rain sensor initiates the communication andsends a signal to its receiver as soon as a rain threshold has beenexceeded. In contrast, according to several embodiments, the sensor unit12 sends measurement information to the interface unit 14, and theprocessing of the data and determination of whether or not to interruptand/or adjust irrigation occurs at the interface unit 14. Additionally,according to some embodiments, the interface unit 14 initiates thecommunication between the sensor unit 12 and the interface unit 14periodically or when it detects that an irrigation cycle is to beinitiated. The sensor unit 12 sends a signal to the interface unit 14after receiving a request or query from the interface unit 14.

It is also known that the threshold level of existing rain sensors maybe adjusted by making a mechanical adjustment to the sensor unit, suchas described in U.S. Pat. No. 6,570,109 to Klinefelter (which isincorporated herein by reference). However, since the sensor unit islocated on a roof top or other similar location such that it may beexposed to the environment and be relatively tamperproof, it is verydifficult to easily adjust the threshold level of rainfall that willtrigger the interruption of irrigation. Several present embodimentsaddress this concern by providing a manual adjustment of the thresholdlevel at the interface unit 14, since in some embodiments the interfaceunit 14 is the portion of the rain sensor system 10 that determines ifthe threshold has been exceeded. In other embodiments, the adjustmentmay be made at the interface unit 14 and/or controller 30 andtransmitted to the sensor unit 12. The interface unit 14 is typically ina location that is far more easily accessible to the user; thus, theuser may more easily adjust the rain threshold in use, e.g., to accountfor seasonal changes.

Additionally, known rain sensors only interrupt irrigation when the rainfall exceeds a fixed threshold. In contrast, according to severalpresent embodiments, the sensor unit 12 sends measurement data to theinterface unit 14 and the interface unit 14 analyzes the atmosphericmeasurement data to permit or interrupt irrigation based on one or moredifferent considerations such as the amount of rain fall, the current orsensed temperature, the rate of change in the rain fall amount ortemperature or the combination of several criteria.

In many embodiments, the sensor unit 12 sends data, and receivesrequests or queries for sensed data from the interface unit 14 through acommunication link 15. The communication links 15 described herein maybe any wireline or wireless communication link. Generically, theinterface unit 14 includes an input/output unit 18, which willcorrespond to the specific communication link 15. For example, in awireline communication link 15, the input/output unit 18 will be awireline signal transmitter, a wireline signal receiver and a wirelineconnector. However, in a two-way wireless communication link 40 (seeFIG. 2), the output takes the form of a wireless transceiver 44, such asa radio, optical, infrared, and/or ultrasonic transceiver. Furthermore,the input/output unit 16 of the sensor unit corresponds to thecommunication link 15. For example, in a wireline communication link 15,the input/output unit 16 will be a wireline signal transmitter, awireline signal receiver and a wireline connector. However, in awireless communication link 40 (see FIG. 2), the input/output unit 16takes the form of a wireless transceiver 42, such as a radio, optical,infrared, and/or ultrasonic transceiver. Advantageously, the wirelesscommunication link 40 of FIG. 2 allows for easier installation since awireline connection is not required between the sensor unit 12 and theinterface unit 14. It is understood that in some embodiments, both theinterface unit 14 and the sensor unit 12 each have a transmitter and aseparate receiver, instead of a transceiver, and in some instancesincludes input/output interfaces for both wired and wirelesscommunication.

The interface unit 14 may be coupled to the irrigation controller 30 indifferent ways depending on the controller 30 and user preference. Insome embodiments, the output lines 36 may be connected from aninput/output unit 20 of the interface unit 14 direct to an interface 38(e.g., a rain sensor input) of the controller 30. In the event theinterface unit 14 determines or receives an indication that arelationship exists between a threshold or other criteria and themeasurement data and/or in the event that a threshold has been exceeded,a switch is closed within the output 20 completing a circuit causing acurrent to flow through the output lines 36 to the interface 38. Thecontroller 30 is configured to sense this current, and in response, thecontroller 30 temporarily halts the execution of one or more wateringschedules and/or determines other appropriate actions. The currentflowing through the output lines 36 is switched off after a period oftime, in response to instructions or reset from the controller and/or inresponse to a data transmission, or a reply from the sensor unit 12 to asubsequent data request (e.g., when the precipitation data has returnedto below the threshold level and/or the relationship between thethreshold level and other criteria and the measured data no longerexists). In this case, the controller 30 senses the absence of thecurrent at the interface 38 and resumes normal execution of wateringschedules. In another embodiment, the signal from the input/output 20 isa data signal that includes a message instructing the controller 30 totemporarily halt execution of one or more watering schedules until asubsequent resume data signal is sent.

In a further embodiment, rather than coupling to an interface 38 of thecontroller, the interface unit 14 couples in series with the common line34 of the activation lines 32. For example, the common line 34electrically passes through the output 20 (e.g., a switching device) ofthe interface unit 14. When the interface unit 14 determines or receivesan indication that a rain threshold has been exceeded and/or that othercriteria have been met, the interface unit opens the switching device,breaking the common line 34. This effectively disables all electricalsignals via the activation lines 32 to the valves, until the switch isclosed. In this way, the controller 30 is not aware that the wateringhas been interrupted or overridden. It is noted that in someembodiments, the interface unit 14 may be integrated into thefunctionality of the controller 30.

Alternatively, in some embodiments, the interface unit 14 may forwardthe measurement data or the determination that some criteria has beenmet, e.g., a threshold has been exceeded or other relationship existsbetween the measurement data and some criteria, to the irrigationcontroller 30, where the processor or the irrigation controller willinterrupt rain fall based on the received information.

In some embodiments the interface unit 14 may be implemented as a partof the irrigation controller 30 and/or located on or integral to theirrigation controller. In one embodiment, for example, the interfaceunit is implemented as a module that may be inserted into a modularirrigation controller. FIG. 33 illustrates an exemplary embodiment of amodular irrigation controller 3300 having an interface unit module 3312.The modular controller 3300 comprises a display 3302, a rotary dial3304, one or more user inputs 3306, a base module 3307, one or moreexpansion modules 3308, a sensor connection 3310, and an interface unitmodule 3312, all generally contained within a housing 3314. Generally,modular irrigation controllers are known in the art to be controllersthat accept expansion modules to provide additional station or zoneoutputs. Further details of various modular controllers are described inU.S. patent application Ser. No. 11/022,179 and published as U.S. PatentApplication Publication No. 2005/0273205, the entirety of which isincorporated herein by reference. In one embodiment, a base module 3307is provided that includes output connectors for the master valve (MV),common line (COM), and a number of station outputs (3 are illustrated inthe base module 3307). Each expansion module 3308 includes an additionalnumber of output connectors to allow connection of activation lines toactuate additional stations (in this case, three additional stationoutputs are provided with each module 3308).

In one embodiment, the interface unit module 3312 is coupled a modulemounting location instead of an expansion module. The interface unitmodule 3312 includes an antenna 3316 (one embodiment of an input/outputunit 18) to communicate with one or more sensor units 12. In oneembodiment, the interface unit module 3312 includes two connectors thatallow wires 3318 and 3320 to connect to the terminals or connections ofthe sensor connection 3310, where the sensor connection 3310 provides away to connect to the common line 34 without having to cut the commonline. It is noted that in this case, the wires 3318 and 3320 wouldreplace a wire connecting the two terminals of the sensor connection3310 together. In several embodiments, the interface module unit 3312 isnow coupled in series with the common line 34. When the interface unitmodule 3312 determines that irrigation should be interrupted or when itreceives an indication that a rain threshold has been exceeded and/orthat other criteria have been met, the interface unit module 3312 opensan internal the switch, breaking the common line 34. This effectivelydisables all electrical signals via the activation lines 32 to thevalves, until the switch is re-closed.

Alternatively, in another embodiment, the sensor connection 3310 isconfigured for connection to the microcontroller of the modularcontroller 3300. For example, when the interface unit module 3312determines that irrigation should be interrupted, the interface unitmodule 3312 causes a current to flow to the sensor connection. Themicrocontroller detects that presence of current flow at the sensorconnection, which indicates to the microcontroller that irrigationshould be interrupted and the microcontroller causes the interruption.In several embodiments, the interface unit module 3312 gets operationalpower from the backplane connection of the module to the controller3300. The above embodiments, allow the interface unit module 3312 tooperate when connected to a module mounting location of the modularcontroller 3300 without sending control signals directly from the module3312 to the microcontroller, since many modular controllers will nothave sufficient programming to process such direct control signals.However, in other embodiments, the interface unit module 3312 directlyoutputs irrigation interrupt signals to the microcontroller via thebackplane connections between the module mounting location and themicrocontroller.

In one embodiment the interface unit module 3312 is inserted within themodular controller 3300, draws power therefrom and is coupled to aninterface unit 14 mounted externally. In this embodiment, according toone implementation, the interruption is controlled by the externalinterface unit 14. In one embodiment, the interface unit 14 sends thedetermination to interrupt irrigation to the interface unit module 3312and the interface unit module 3312 interrupts irrigation according toone or embodiments described above (e.g., breaks the common, or outputsa signal to the microcontroller which interrupts irrigation). In anotherimplementation, the interface unit module 3312 includes a display andbuttons, etc., to create a user interface to allow a user to program theinterface unit module 3312 while it is inserted into the modularcontroller 3300. In another embodiment, the interface unit module 3312outputs signals to the microcontroller of the modular controller 3300and uses the user interface of the modular controller to allow the userto configure the interface unit module 3312.

Referring again back to FIGS. 1 and 2 and in a further embodiment, theinterface unit 14 will continue to indicate to the controller 30 that itshould remain off even after the precipitation data has returned belowthe threshold and/or other conditions no longer exist. For example, fora period of time after the precipitation data returns below thethreshold level, the interface unit 14 continues to allow current toflow to the interface 38, continues to send the appropriate controlmessage signaling to the interface 38, delays sending a control messageinstructing the controller to resume watering, or continues to break thecommon line 34. This delay in re-enabling the controller is settable bythe user on the interface unit 14 and allows the system to postponeirrigation for several days after a heavy rain has occurred. In otherembodiments, the delay can be automatically controlled, for example,using equations involving one or more of temperature, dry out rate, etc.This embodiment allows for increased water conservation.

In some embodiments, as illustrated in FIGS. 1 and 2, the interface unit12 and the sensor unit 14 are coupled via a two-way communication link15. The communication link 15 may be a wired communication, asillustrated in FIG. 1, or a wireless communication as illustrated inFIG. 2. The two-way communication link 15 enables the sensor unit 12 andthe interface unit 14 to send and receive signals, including one or moreof data, status information and control signals to and from one another.For example, in one embodiment, the interface unit 14 sends controlsignals to the sensor unit 12 and, depending on the control signal, thesensor unit 12 takes the appropriate action/s. For example, in oneembodiment, the interface unit 14 may send a request to the sensor unit12 for data. The sensor unit 12 may, in response to the request,generate the data and send it via the two-way communication link 15 tothe interface unit 14. Further, in some embodiments, the interface unitsends control signals to the sensor unit 12 over the two-waycommunication link 15, wherein the sensor unit receives the signal andmakes an adjustment or change based on the control signal received. Inone embodiment, the control signal from the interface unit 14 causes thesensor unit 12 to change a mode of operation (e.g., such as entering alow power or hibernation mode). Additionally or alternatively, thesensor unit 12 sends signals, e.g., including data, information and/orcontrol signals, to the interface unit 14, and the interface unit isadapted to receive the information and take actions and/or makedeterminations based on the information. For example, the sensor unit 12may transmit information corresponding to an amount of rain and/ortemperature sensed at the sensor unit 12. This information may be ameasurement of rain fall or an indication that a threshold amount ofreceived rain fall has been exceeded. In several embodiments, theinterface unit 14 receives a measurement of rain fall and/or temperatureand makes a determination of whether or not to interrupt irrigationbased at least in part on the received measurements. The interface unit14 is adapted to cause an interruption of irrigation if it is determinedthat irrigation should be interrupted. Further, the sensor unit 12 andinterface unit 14 may both comprise transceivers 16 and 18 (wired orwireless) wherein the transceivers are capable of sending and receivingsignals to one another over the two-way communication link 15.Alternatively, in one embodiment, the sensor unit 12 and the interfaceunit 14 each have separate transmitter and a separate receiver.

It is noted that in many embodiments, the interface unit 14 isconfigured to break the common line 34 of an irrigation controller. Inalternative embodiments, the interface unit 14 is coupled to and canbreak one or more individual activation lines 32. That is, the interfaceunit 14 may be coupled in series with one or more of the activationlines 32. When the interface unit 14 determines or receives anindication that a rain threshold has been exceeded and/or otherwisedetermines that irrigation should be interrupted, the interface unit 14opens the switching device, breaking one or more of the activationlines. In this embodiment, the interface unit 14 may be adapted tointerrupt irrigation for a specific set of activation lines whileallowing irrigation for valves coupled to other activation lines. Thebreaking of the one or more activation lines 32 disables the electricalsignals from those one or more activation lines 32 to the valves, untilthe switch is closed.

Referring next to FIG. 3, a diagram is shown of the functionalcomponents of some embodiments of a sensor unit 12 of the rain sensorsystem 10 of FIGS. 1 and 2. The sensor unit 12 includes a controller312, a memory 314, and a transceiver 316. The sensor unit furtherincludes and/or cooperates with a rain sensor 318. The controller may beimplemented through a single-processor or multiprocessor systems,minicomputers, microprocessor, processor, programmable electronics andthe like, and/or combinations thereof.

The memory may be a separate memory unit within the sensor unit 12,external memory connected to the sensor unit via an interface (notshown), may be internal memory within the controller 312 as illustratedin FIG. 3, and/or other such configurations. The controller 312 and thememory 314 together function as a microcontroller. In some embodiments,memory 314 comprises one or more of a random access memory (RAM), readonly memory (ROM), Flash memory, an EEPROM memory, on-chip RAM, opticaldisk storage, and/or any other medium which may be used to store thedesired information and which may be accessed by the controller. In someembodiments, the microcontroller employs flash memory for storage ofexecutable firmware, and is capable of being programmed “in-system”.This may be accomplished in some instances by employing an in-systemprogramming port in the unit 12 and/or on a printed circuit board, forexample of the controller, for accomplishing the programming processduring a final assembly. In some embodiments, the microcontrollerfurther includes an EEPROM for non-volatile storage of miscellaneousdata to support at least some of the functionality of the controller.Additionally or alternatively, on-chip RAM may be present in sufficientquantity to provide functional capabilities in many embodiments.

The sensor unit 12, in some instances, further includes a power source324, such as a battery, solar cell, wind powered generated and/or othersuch power source, to power the components of the sensor unit 12. Forexample, the sensor unit 12 operates from a high capacity lithium-ionbattery. As illustrated in FIG. 3, in some embodiments, the controllerincludes an on-chip analog-to-digital converter (ADC) 326. The ADC may,for example, have an 8-bit resolution or greater, and contain four ormore input channels. In other embodiments, the ADC may be a separateunit within the sensor unit 12, or separate components within the sensorunit may comprise a separate ADC.

The transceiver 316 provides wired and/or wireless communication.Wireless radio frequency chips known in the art such as TexasInstruments CC1100, Melexis TH71211, Micrel MICRF112, or MICRF211,Semtech CE1201A, Atmel ATA5428, Analog Devices ADF7020 or ADF7021,and/or Maxim MAX7033 or MAX7044 may be used for the transceiver 316. Thewireless transceiver includes or couples to an antenna. In someimplementations, the transceiver comprises a single-chip transceiverthat provides an analog or digital Received Signal Strength Indicator(RSSI) output signal. If the RSSI output is an analog signal, it may besupplied initially to one channel of the ADC 326.

In some embodiments the sensor unit 12 may include and/or may couplewith several additional sensors, such as a temperature sensor 322, abattery voltage sensor 320 as shown in FIG. 3, and/or other suchsensors. The battery voltage sensor 320 is connected to the power source324. The temperature sensor 322 may be any temperature-sensitive devicesuch as a thermistor, temperature-dependent current device, and thelike. In some embodiments, the temperature sensor is capable ofdetecting an ambient temperature of between about, 150 to 0° F., forexample detecting an ambient temperature of about 35-39° F., e.g., 37°F., with a tolerance of ±5% or better.

The rain sensor 318 reacts to the presence of water and generally reactsproportionally to the amount of water (rain fall) received, for examplein one embodiment, the rain sensor generates an electrical signal thatis indicative of a level of precipitation or rain. This electricalsignal represents precipitation data. In some embodiments, the outputsignal is an output voltage signal of the rain sensor 318 that isprovided to one channel of the controller's ADC 326. In someembodiments, the level indicated by the electrical signal is transmittedto the interface unit 14 via transceiver 316 periodically and/or whenthe sensor unit determines that a change has occurred in the amount ofrain fall, and/or stored in memory for future access. For example, inthis or other embodiments, the level indicated by the electrical signalis stored in the memory 314 and upon receiving a request from theinterface unit 14 the controller 312 retrieves the data from the memory314 and forwards the data to the transceiver 316 to be transmitted tothe interface unit 14. Additionally or alternatively, the rain sensormay detect that a threshold level of rain or precipitation has beenreceived and in response generate a signal that indicates that thethreshold level of rain has been exceeded.

In other embodiments, the rain sensor may output signals from thetemperature sensor 322 and/or the battery voltage sensor 320 that may,for example, additionally or alternatively be provided to two otherchannels of the ADC 326, and the indicated levels stored in memory 314,to be supplied to the interface unit 14 periodically, upon detecting achange, and/or upon receiving a request from the interface unit. In someembodiments, the signal or measured levels may not be stored, andinstead the controller 312 may retrieve the information from one or moreof the sensors at the time of transmission and/or when a request isreceived from the interface unit 14. For example, in one embodiment thesensor unit 12 requests measurements from the sensors at fixedintervals, e.g., every 5 minutes, and may additionally process the datato determine whether a change has occurred since the last receivedmeasurement. The controller 312 may generate a data signal based on theelectrical signals received from the sensors, and may transmit the datasignal to the interface unit 14 via the communication link 15.

In some embodiments, the measured data transmitted to the interface unit14 is simply a measurement and does not include an indication that athreshold has been exceeded. Instead, the determination whetherirrigation should be permitted or interrupted (e.g., whether arelationship exists between certain criteria and the data, such as whena threshold has been exceeded) is made at the interface unit 14 and/orirrigation controller 30 based on the received measurements from thesensor unit 12. Alternatively, in other embodiments, the controller unit312 may be configured to determine if a predefined relationship existsbetween the measurement and a level or threshold, and transmit thatdetermination to the interface unit 14 upon receiving a request from theinterface unit 14. The sensor unit 12, in some implementations, does nottransmit measurement data regarding the information obtained through thesensors to the interface unit 14 unless and until it receives a requestfrom the interface unit 14 for such data. Alternatively, the sensor unit12 may transmit the measurement data to the interface unit 14 atintervals, e.g., 6 hour intervals, or when it determines a change in themeasurement data in addition to providing the data to the interface unit14 upon receiving a request for the data. Further, the information maysimply include an indication that a threshold has been exceeded. Inother implementations, the information provided may include a level ormeasure of rain.

In some embodiments, the rain sensor 318 comprises a sensor andcontroller circuitry where upon sensing a level of precipitation thesensor will cause an electrical voltage to be generated by the controlcircuitry. The sensor and circuitry may take different forms indifferent embodiments. By way of example, in some embodiments, the rainsensor 318 includes a moisture absorptive material that expands andcontracts based on the presence of and absence of rain fall, such as ahygroscopic material. The level or amount of expansion or contraction issensed or measured and provided as an electrical signal. The leveland/or measurement data is then transmitted by the transceiver 316 tothe interface unit 14, wherein in some implementations, the interfaceunit determines if a rain threshold has been exceeded and/or if otherrelationship exists between the measurement data and certain criteria.In some embodiments, the electrical signal corresponding to the level ofrain fall is converted to a measure of the amount of rainfall prior tobeing sent to the interface unit 14, and/or an indication of arelationship of the measurement relative to a threshold may be forwardedto the interface unit 14. Alternatively, the expansion of the absorptivematerial may cause activation of a switch when a preset level of rain isreached. Upon activation of the switch the control circuitry may send asignal to the controller and then store the indication in memory. Inthis embodiment, when a request from the interface unit is received forrain levels an indication that the preset level was reached istransmitted by the transceiver 316 to the interface unit 14. In someembodiments, the rain sensor will not generate any signals untilinformation is requested from the rain sensor, at which time the sensortransmits a signal indicating the measurement of rain fall or the signalindicating that the switch is activated. Alternatively, the sensor unit12 may initiate transmission to the interface unit 14 based on themeasurement data. For example, in one embodiment, the sensor unit 12will process the signal indicating the measurement of rain fall orsignal indicating that the switch has been activated to determine if achange in the atmospheric conditions has occurred. In this embodiment,if the sensor unit 12 determines that a change has occurred it willforward the signal to the interface unit 14. Additionally oralternatively, in one embodiment, the sensor unit will initiatetransmission to the interface unit 14 forwarding the signal at fixedintervals, e.g., every 6 hours. In some embodiments, the interface unit14 may send a request to the sensor unit 12 requesting that the sensorunit obtains current and/or updated data from the sensors prior to theinitiation of an irrigation cycle and/or at other times, for example,when the user requests the data through the user input, and or by othermeans. In some embodiments, for example, when the interface unitdetermines that an irrigation cycle is about to begin the interface unitmay send a message to the sensor unit 12 requesting current data todetermine whether to inhibit irrigation. In one exemplary embodiment,the interface unit may send a message to the sensor unit 12 requestingdata when the operator of the interface unit has requested the data. Forexample, in one exemplary embodiment, the operator may periodicallyrequest data, for example, through the user input 424 (see FIG. 4), toensure that the sensor unit 12 and the system 10 as a whole are workingproperly. The receipt of a signal from the sensor unit 12 with dataindicates that the sensor unit is properly working. Additionally, insome embodiments, the sensor unit 12 also sends its battery strength.This allows the operator send a test request message to the sensor unit12 to determine if it is working. Additionally, in some embodiments, thesensor unit 12 sends data indicating the battery strength or batterylife (and thus, approximately when the battery of the sensor unit willneed to be charged or replaced).

Alternatively, in embodiments where the sensor unit 12 initiatestransmission to the interface unit 14, the rain sensor may generate asignal comprising the measurements and/or other data and transmit thesignal to the interface unit 14 upon making some determination, e.g.,that a change in one or more parameters has occurred and/or othercriteria has been satisfied, and/or at fixed intervals.

The shape and configuration of the hygroscopic material may be varieddepending on the implementation. In some embodiments, the hygroscopicmaterial is in the form of one or multiple disks. In another embodiment,the hygroscopic material is a granular and expandable material within aflexible envelope or casing. For example, the granular material mayinclude polyacrylamide or similar materials.

In several embodiments, the sensor unit 12 operates in one of severalmodes. The mode of operation may depend on one or more factors, such asbattery charge level or expected battery life, weather and/oratmospheric conditions, anticipated requests for data and/or other suchfactors. The modes may be adjusted internally by the controller 312and/or externally by the user via the user input 424 and/or by othermeans. In one implementation, the sensor unit 12 is in a sleep orquasi-powered down mode, which in some implementations, is a “normalmode”, which is in some embodiments the mode that the sensor unit 12 ismost often operating in. The sensor unit 12 reduces and/or attemptsminimize power consumption while in the sleep mode to better conservepower and/or maximize battery life. In some embodiments, while in thenormal or sleep mode the sensor unit 12 does not initiate a transmissionto the interface unit 14, and in some instance, will never initiate atransmission to the interface unit 14. In other embodiments, duringnormal or sleep mode the sensor unit will initiate transmissions to theinterface unit 14, for example at fixed intervals and/or when somecriteria are met, e.g., when there is a change in one of rain fall,temperature, and/or other parameters.

In some embodiments, while in the sleep mode, the transceiver 316 may besimilarly put into a sleep mode, where many of the components of thetransceiver are powered down, while the transceiver is still capable ofdetecting the presence of an incoming message without needing to applyfull power to all circuitry. In several implementations, during thesleep mode the sensor unit 12 is capable of receiving requests initiatedby the interface unit 14. The sensor unit may further receive requestsfor other information and/or operating parameters, such as requests forthe measurements received by the sensors employed with the sensor unit,the signal strength, the transmittal power, identification informationof the sensor unit, and/or a variety of other information. In oneembodiment, after receiving requests from the interface unit 14 and/orother devices, the controller 312 will determine what information isrequested, and will retrieve the information and/or initiate ameasurement of the requested information by the sensors. In someembodiments, the measurement(s) by sensors occurs periodically, and themeasurement data is forwarded to transceiver 316 and transmitted to theinterface unit via communication link 15. Alternatively, in someembodiments, the data obtained is stored onto the memory 314.

FIG. 23 illustrates an example implementation of a process 2300 ofoperating in sleep or normal mode at the sensor unit 12, according tosome embodiments. Normally, in the step 2302, the sensor unit is insleep mode. Accordingly, the sensor unit operates in a low battery usagestate with only minimal portions of the controller 414 runningPeriodically, the sensor unit wakes up in step 2304. For example, thecontroller and other electronics of the sensor unit enter a normal powerusage mode. In step 2310, once awake, the sensor unit 12 queries thesensor/s and other devices and generates measurements. In someimplementations, these intervals are predefined. Alternatively, in otherembodiments, the sensor unit may adjust the rate at which it will wakeup and query the sensors based on the amount of rain fall, thetemperature, the rate of change of rain fall and/or temperature, and/orother such criteria. In some embodiments, the sensor unit 12 then storesthe measurements in the memory 314 for later processing. Alternatively,the sensor unit processes the data as soon as it is received from thesensors and other peripheral devices. Next, in step 2312, the sensorunit 12 processes the measurement data received from the sensors. Thesensor unit 12 may process the signals to generate measurements to besent to the interface units, and/or process the data to determinewhether the data satisfy certain relationships and/or criteria. Forexample, in one embodiment, the sensor unit 12 analyzes the datareceived from the rain sensor 318 and temperature sensor 322 todetermine a rate of rain fall, a rate of temperature and/or whetherthere is a change in the amount of rain fall and/or temperature.

In step 2314 the sensor unit 12 determines if a request for data hasbeen received from the interface unit 14. When the sensor unitdetermines that a request has been received, in some embodiments, theprocess continues to step 2320 where the sensor unit 12 transmits asignal to the interface unit. For example, the controller 312 of thesensor unit constructs a message comprising data such as the obtainedmeasurement data, e.g., rain fall and precipitation data, temperature,battery strength, signal strength of the received request, and/or otherdata into one or more data packets to be forwarded to the transceiver316 to be transmitted to the interface unit 14. The sensor unit thenreturns to the low power or sleep mode of step 2302.

Alternatively, if no request has been received from the interface unit14, the process moves to step 2316 where the sensor unit determines ifthere has been a change in the sensor data, for example, if there hasbeen a change in sensed atmospheric conditions and/or other criteriahave been met. For example, in one embodiment the sensor unit mayprocess the data to determine whether there is a change in the amount ofrain fall or temperature determined in step 2312. In one embodiment, thesensor unit may retrieve the results of the determination from thememory 314 to determine whether a change has occurred. Alternatively,the sensor unit may retrieve the data from the memory 314 for currentand previous data and/or query the sensors for the data before makingthe determination in step 2316. If the sensor unit 12 determines that achange has occurred in one or more of the sensor data, then the processwill continue to step 2320 where the sensor unit will send or transmit asignal to the interface unit comprising, for example, the measurementsretrieved from the sensors, signal strength, and/or other data availableat the sensor unit 12. The sensor unit then returns to the low power orsleep mode of step 2302. If, however, in step 2316 the sensor determinesthat no change has occurred in the atmospheric parameters, the processmoves to step 2318 where the sensor unit determines if it is time for aperiodic update to be sent to the interface unit. In one embodiment, thesensor unit 12 sends updates to the interface unit 14 at fixedintervals, e.g., every 6 hours. The updates may be sent to ensure theinterface unit that the sensor unit is working and that the connectionbetween the sensor unit and the interface unit 14 has not failed. If instep 2318 the sensor unit 12 determines that it is time for a periodicupdate, then it moves to step 2320 and sends a signal to the interfaceunit 14, and then returns to the sleep mode in step 2302. Alternatively,if it is not time for an update, then the sensor unit returns to step2302 when it enters sleep mode before then proceeding back to step 2304.

In some embodiments, the content of the message or packet may vary basedon different criteria or situation. For example, in one embodiment, thecontents of the packet may depend upon the type of request received fromthe interface unit. For example, a SENSOR_STATUS_REQUEST message may bereceived at the sensor unit from the interface unit 14. Upon receipt ofthis message, the sensor unit 12 initiates a measurement of theprecipitation level, ambient temperature, full-load battery voltageand/or other parameter depending on the received request according tosome embodiments. The sensor unit may query the sensors to obtain suchmeasurements, and/or retrieve the measurements from the memory 314.After these one or more measurements have been obtained, the sensor unit12 constructs a message packet containing the results of themeasurements along with the RSSI value that was observed during thereceipt of the message. The entire message packet is then transmitted tothe interface unit 14 in the form of a SENSOR_STATUS message. In someembodiments, in addition to information requests, while in the sleepmode, the sensor unit 12 may also receive “set” commands from theinterface unit 14. These commands provide a value for one or morevariables stored in memory within the sensor unit 12, such astransmittal power, threshold values, etc. Upon receiving such messages,the sensor unit 12 will store the value and transmit an acknowledgemessage to the interface unit 14.

In some embodiments, the sensor unit periodically monitors its storedpower level and/or battery life while in the sleep mode. A process 510by which the sensor unit monitors the battery life, according to someembodiments, is illustrated in FIG. 5. In step 512 the sensor unit 12transitions out of the sleep or low-power mode. In step 514 the sensorunit activates one or more sensors and/or other peripheral systems in orcooperated with the sensor unit 12. In some instances, the transmitterand/or transceiver is not powered up or only the transceiver or portionsof the transceiver are active.

The power or battery voltage level of the power source 324 is measuredin step 516. In step 518, it is determined whether to enter alow-battery mode. This determination may be made by comparing a measuredfull battery voltage level measured while the sensors and otherperipheral devices have been activated with a non-volatile constantvalue stored in memory 314 to determine if the power source 324 isnearing the end of its useful life or is below a threshold. In someembodiments, in order to accurately make this determination, thecontroller 312 may make a measurement of the ambient temperature, viathe temperature sensor, to calibrate the measured battery voltage. Ifthe battery is approaching the end of its life (e.g., the full-loadbattery voltage is below the minimum allowable voltage) the process 510continues to step 522 where the controller 312 switches the sensor unit12 into a low battery mode and attempts to reduce power consumption byeliminating or reducing the functions performed and/or the frequency ofperforming non-essential functions.

Once the sensor unit 12 enters a low battery mode, step 524 is enteredwhere the sensor notifies the interface unit 14 that it has detected alow battery condition. In some instances, the sensor unit 12 initiatesthe transmission of a warning message to the interface unit 14 at orbelow the transmission power last assigned by the interface. In step526, it is determined whether an acknowledgement has been received fromthe interface unit 14. If the acknowledgment is not received (typicallywithin a predefined period of time), the process continues to step 528where the transmission power is increased and the process returns tostep 524 to again transmit the warning message at the increased powerlevel. The power is increased with each subsequent attempt until anacknowledgment is received, a predefined number of attempts are madeand/or a predefined transmission power level is reached. In someembodiments, the loop through steps 524, 526 and 528 may be repeatedafter a period of time when an acknowledgement is not received.

In some embodiments when an acknowledgment is received from theinterface unit 14, the sensor unit 12 continues to step 530 where itadjusts the number of periodic updates it sends to the interface unit.For example, in one embodiment, where the sensor unit may send 4periodic updates each day to the interface unit during normal mode, onceit enters Low Battery mode the sensor unit may only send 1 periodicupdate per day to the interface unit. In some embodiments, the sensorunit 12 may also reduce the frequency at which it wakes up to query thesensors and/or other peripheral devices for information such as amountof rain, temperature, battery strength and/or other such data once itenters the Low Battery Mode of operation. Alternatively, in someembodiments, after receiving the acknowledge message, the sensor unit 12will not initiate further transmissions other than in response torequests received from the interface unit. The interface unit 14, uponreceiving the warning message, may notify a user, such as displaying amessage on a user display of the interface unit 14 alerting the user ofthe operational mode of the sensor unit 12. Returning to step 518, if itis determined that the end of battery life is not approaching the systemcontinues to step 520 where the sensor unit continues to operate and/orreturns to operating in normal or sleep mode.

In some embodiments, the sensor unit 12, will perform the batterymonitoring process 510 once per day to obtain a current battery voltagelevel and stores the measurement in memory 314, and/or forwards themeasurement to the interface unit 14. Alternatively, in someimplementations, it may not be necessary to perform battery monitoringprocess 510 often since the low battery usage of the sensor unit 12allows the battery or power source to function for long periods of time,and usage of power sources such as solar or wind power energy allowslonger battery life so that the monitoring of the battery life does nothave to be performed frequently.

Further, in some embodiments, the sensor unit may operate in a “LowTemperature” or “hibernate” mode. The sensor unit 12, according to somepossible implementations, may enter low temperature mode when itdetermines that the temperature is below a certain threshold. FIG. 25illustrates one possible implementation of the low temperatureoperational mode, according to several embodiments. In step 2510, whilein normal mode, the sensor unit will periodically, e.g. every 5 minutes,query the temperature and/or other sensors to determine the currenttemperature and other current values. Next, in step 2512 the sensor unit12 will process the measurements and uses the measurement to determineif a certain relationship exists between the measurements, e.g.,temperature, and a freeze threshold level in step 2514. For example, afreeze threshold level may be set at 36 degrees Fahrenheit. If in step2514, the relationship does not exist, the sensor unit will remain innormal mode (step 2516) and cycle back to step 2510. If in step 2514,the sensor unit determines that the relationship exists, the processwill move to step 2518 where it will generate and send a low temperaturemessage or warning to the interface unit 14. Next, in step 2520 thesensor unit receives an acknowledgment message from the interface unit.In one embodiment, when the sensor unit 12 sends the low temperaturemessage or warning and does not receive an acknowledgment it mayretransmit the message for a certain period of time, e.g., five minutes,and or a certain number or retransmissions until acknowledgment isreceived. In some embodiments, the sensor unit 12 will increase itstransmit power with each retransmission up to its maximum allowedtransmit power. In one embodiment, if the acknowledgment is not receivedafter the certain period of time and/or the certain number ofretransmissions the sensor will monitor the ambient radio noise todetermine if a certain level of noise exists. If the sensor unit 12determines that noise exists, the sensor unit will wait a certain amountof time and check back to see if the noise goes away. When the sensorsees an opportunity to send in a noise free time period, it willretransmit the temperature message. In one embodiment, when the sensorunit determines that a noise free time does not exist, and or is notcapable of retransmitting after a certain period of time, the sensorunit 12 will assume that the interface unit 14 is broken, has lost poweror is powered down. Accordingly, the sensor unit 12 will stop trying tocommunicate and listens periodically to see when the interface unit isready for communications and can receive transmissions. In someembodiments, when the interface unit does not hear a response from thesensor unit, the interface unit will cease transmissions so as not toclutter the air waves and listens constantly for communications from thesensor unit 12.

After the sensor unit 12 receives the acknowledgement message, it entersthe low temperature mode in step 2522. In one embodiment, the sensor maydecrease the rate at which it sends updates to the interface unit 14.Additionally or alternatively, the sensor unit may also decrease thefrequency at which it wakes up to query the sensors and/or other localor peripheral devices for data. While in the low temperature mode, instep 2524 the sensor unit will query the temperature and/or other data.Next, in step 2524 the sensor unit uses the sensed temperature data todetermine if the condition still exists at fixed intervals, e.g. onceper day. For example, the sensor unit 12 may measure the temperature anddetermine whether the temperature exceeds a certain threshold. When, instep 2526 the sensor unit determines that condition still exists, e.g.,that the temperature is still below a certain threshold level, in step2528 the sensor unit generates an update message comprising themeasurement of temperature and possibly other data and transmits themessage to the interface unit 14. Further, in step 2528 the sensor unitmay make certain determinations to adjust its mode of operation, whileremaining in low temperature mode. For example, in several embodiments,the sensor unit will measure the battery strength to determine if itneeds to enter into the low battery mode. Next, the sensor unit returnsto step 2524 where it will periodically, e.g. once per day, andprocesses the measurements, in step 2526 to determine if the atmosphericconditions have returned to a normal condition, e.g. temperature isabove the threshold. When in step 2526 the sensor unit determines thatthe conditions have returned to normal, e.g. the relationship betweenthe temperature and/or other data and the threshold no longer exists, instep 2530 the sensor unit will query sensor and other local sensor anddevices for data such as rain amount, temperature, battery strength,signal strength and/or other data and transmits an update message to theinterface unit 14 in step 2532 comprising some or all of the data. Next,in step 2534 the sensor unit enters Normal mode and the process willbegin again at step 2510.

The sensor unit 12 may also operate in a “test mode” in someembodiments. In many embodiments the test mode is utilized, in part,during the installation of the sensor unit 12 to provide the installerwith a relatively quick and simple-to-understand process for testingthat the sensor unit 12 is installed at a location with, for example,adequate radio reception from the interface unit 14. The installationprocess is described in further detail below.

Referring next to FIG. 4, a diagram is shown of the functionalcomponents of some embodiments of the interface unit 14 of the rainsensor device of FIGS. 1 and 2. The interface unit 14 comprises atransceiver 412, a controller 414, a relay device 416, a memory 418, auser display 426, and a user input 424. In some embodiments, theinterface unit 14 may also include a current sensor 420, and a voltagesensor 422. The components of the interface unit 14 are coupled to oneanother by a bus or other means. The transceiver 412 may be any hardwire, wireless, optical and/or other device capable of transmitting andreceiving signals to and from the interface unit 12 via thecommunication link 15 or 40. Examples of wireless radio frequency chipsknown in the art include Texas Instruments CC1100, Melexis TH71211,Micrel MICRF112, or MICRF211, Semtech CE1201A, Atmel ATA5428, AnalogDevices ADF7020 or ADF7021, and/or Maxim MAX7033 or MAX7044 may be usedfor the transceiver 316. The wireless transceiver includes or couples toan antenna. The controller 414 may be implemented through asingle-processor or multiprocessor systems, minicomputers,microprocessor, processor, programmable electronics and the like, and/orcombinations thereof. The controller 414 and the memory 418, in someimplementations, together function as a microcontroller. The memory 418may be a separate memory unit within the interface unit 14, externalmemory connected to the interface unit via an interface (not shown), maybe internal memory within the controller 414, and/or other suchconfigurations. Further, the memory may comprise one or more of flashmemory, EEPROM memory, RAM, ROM, on-chip RAM, and/or other such memoryor combinations of memory.

In some embodiments, the controller 414 employs flash memory for storageof executable firmware, and is capable of being programmed “in-system”.This may be accomplished in some instances by employing an in-systemprogramming port in the interface unit 14, on a printed circuit board ofthe controller 414 and/or other configurations to accomplish theprogramming process during, for example, a final assembly. In someembodiments, the controller 414 further includes an EEPROM or othernon-volatile memory for storage of data, executables and/or othersoftware to support of the functional capabilities of the controller414. Additionally or alternatively, on-chip RAM may be included on thecontroller 414 in sufficient quantity for functional capabilities inmany embodiments. Generally, the controller 414 executes instructionsstored in the memory 418 to implement the functionality of the interfaceunit 14.

FIG. 24 illustrates a process 2400, according to some embodiments, bywhich, at least in some part, the interface unit 14 provides somecontrol over irrigation. When the sensor unit 12 transmits a signal tothe interface unit 14, the signal is received at the interface unit instep 2412. In some embodiments, the sensor unit 12 will transmit thesignal at fixed intervals, e.g., every 6 hours, and/or when it senses achange, for example, a change in the amount of rain fall or temperature.Additionally, the sensor unit 12 will send signals to the interface unit14 when the interface unit sends a request to the sensor unit requestinginformation as shown in optional step 2410. Alternatively, the signalmay be received in response to a request for data sent from theinterface unit in step 2410.

After receiving the signal, in step 2416, the interface unit processesthe signal to retrieve data such as temperature, amount of rain fall,and/or other data, such as battery strength. After processing the data,step 2422 is entered where the interface unit determines if irrigationis currently interrupted, e.g., if a relay or switch is currently open.When irrigation is not interrupted, in step 2418, the controller of theinterface unit 14 will determine whether to interrupt irrigation. Forexample, in one embodiment, in step 2418, the interface unit comparesthe measurements received from the sensor unit to certain thresholdlevels and/or other criteria to determine whether a relationship existsbetween the measurements, e.g., amount of rain fall and/or temperature,rate of change thereof and the thresholds. Further, in one or moreembodiments, the interface unit 14 may use the data to determine arelationship between current data and previous data received from thesensor unit. For example, in one embodiment the interface unit maydetermine a rate of change in the atmospheric data, e.g., rainfall,temperature, and/or other data. In some embodiments the decision tointerrupt the irrigation is based on whether the measurement dataexceeds certain preset thresholds. Additionally and/or alternatively thedetermination may be based on other criteria. For example, in oneembodiment the sensor unit uses the data to determine a rate of change,and bases the determination at least in part on the calculated rate ofchange.

FIG. 30 illustrates one example of how the decision to interruptirrigation may be based at least in part on the rate of change in theamount of rain fall. An example graph of rain fall amount in inchesversus time in hours is illustrated with two different rain fallprofiles A and B. In both profiles, the rain fall cutoff (or interrupt)threshold 3002 is set at ½ inch. In profile A, the rate of increase ofrainfall is high (indicated by a steep slope on the increasing side ofprofile), and therefore, in some embodiments, the interface unit 14 willinterrupt irrigation before the threshold level is reached, for exampleat point 3004. Alternatively, in profile B, rate of increase of rainfall is less (indicated by the gradual slope of the increasing side ofthe profile), and in that situation, the interface unit 14 may inhibitirrigation after the rain fall amount reaches and/or exceeds thethreshold 3002, for example at point 3006. Thus, when determiningwhether to interrupt irrigation, several embodiments, use at least therain fall measurement and a rate of rain fall.

Referring back to FIG. 24, when in step 2418 the interface unitdetermines that irrigation should be interrupted it will generate aninterrupt signal in step 2420. For example, in one embodiment, theinterrupt signal is a signal to open a relay or switch that to break thecommon line of the irrigation controller. Alternatively, if in step 2418the interface unit determines that irrigation should not be interrupted(irrigation should be permitted) it may continue to step 2430 where itmay determine whether irrigation should be adjusted. Criteria similar tothe determination of whether irrigation should be interrupted may beused to make the determination in step 2430. If the interface unitdetermines that irrigation should be adjusted, it may generate a signal,in step 2432, that cause an adjustment to the irrigation schedule oramount of irrigation. Alternatively, if the interface unit determinesthat an adjustment is not necessary it returns to step 2412 or optionalstep 2410 and repeats the process once a request is initiated and/or atransmission from the sensor unit is received. Alternatively, in someembodiments, once in step 2418 the interface unit determines thatirrigation should not be inhibited it returns to step 2412 or optionalstep 2410 and repeats the process once a request is initiated and/or atransmission from the sensor unit is received.

Returning to step 2422, when the interface unit determines thatirrigation is currently interrupted, in step 2424 the interface unit 14determines whether irrigation should be reactivated. For example, theinterface unit uses the data from step 2416 and determines whethercertain relationship exists between the data and certain levels and orthresholds. For example, the interface unit determines whether arelationship exists between a rain fall threshold and the amount of rainfall indicated by the data received from the sensor unit 12.

Additionally or alternatively, the interface unit may look at the rateof change in one or more atmospheric parameters to determine whether toreactivate irrigation. For example, in FIG. 30 the rate of rain fall inprofile A indicates a gradual decrease in the amount of rain fall at thesensor unit 12 (i.e., it represents a gradual decrease or drying out ofthe sensor material, possibly indicating further rain or slowing rain).As such, the interface unit may reactivate or permit irrigation afterthe amount of rain fall is below the threshold level, for example, atpoint 3008. Alternatively, in profile B the rate of rain fall decreaseis greater (as indicated by the decreasing slope of profile B).Therefore, the interface unit may reactivate or permit irrigation beforethe rain fall amount has fallen below the threshold 3002, for example atpoint 3010. A rapidly decreasing slope could indicate that the rain fallquickly stopped and perhaps that the air is dry such that irrigationshould be permitted sooner.

Returning to FIG. 24, if in step 2424 the interface unit determines thatirrigation should be reactivated or permitted it may generate a signalto reactivate irrigation in step 2426. For example, in one embodiment,the signal may cause a relay or switch breaking the common line of acontroller to close. This would allow irrigation activation lines of thecontroller to function. Alternatively, if in step 2424 the interfaceunit 14 determines that irrigation should remain interrupted, it willreturn to step 2412 or optional step 2410 and repeats the process once arequest is initiated and/or a transmission from the sensor unit isreceived.

FIG. 6 illustrates an alternative process 610 to, at least in part, toprovide some control over irrigation as implemented through theinterface unit 14, according to some embodiments. When an irrigationcycle is initiated or commanded by the irrigation controller 30, theinterface unit 14 is notified (e.g., a current flows in the common line34 that is detected by the interface unit). In step 612, the interfaceunit detects the initiation of an irrigation and/or the notificationthat an irrigation is about to be initiated, for example, the currentsensor 420 detects the current flow through the common line. Followingdetection of the signal, in step 614 the current sensor 420 notifies thecontroller 414 and the controller initiates a transmission of a requestto the sensor unit 12 by the transceiver 412. Alternatively, in someembodiments the current sensor sends a signal to the controller 414indicating the measurement of current flow and the controller determineswhether an irrigation is about to be initiated. Following the detectionof initiation of an irrigation cycle step 614 is entered where thecontroller 414 initiates a transmission of a request to the sensor unit12 by the transceiver 412. In step 616, the transceiver 412 receives asignal carrying data transmitted by the sensor unit 12 in response tothe request, and supplies the data to the controller 414. In someinstances, the signal provides measurement data taken by the sensor unit12 and/or an indication that a threshold has been reached, and themeasurement data or indication is stored or cached in the memory 418. Insome embodiments, the interface unit 14 may send a request to the sensorunit 12 requesting that the sensor unit obtains current and/or updateddata from the sensors prior to the initiation of an irrigation cycle. Insome embodiments, for example, when the interface unit determines thatan irrigation cycle is about to begin the interface unit may send amessage to the sensor unit 12 requesting current data to determinewhether to inhibit irrigation.

In step 618, the interface unit 14 determines whether the irrigationcycle should be inhibited. Alternatively, the measurement data isforwarded to the irrigation controller 30 to evaluate and determinewhether irrigation is to be interrupted. The signals received at theinterface unit 14 from the sensor unit 12 may comprise an indicating athreshold level has been exceeded, data corresponding to a level ofprecipitation and/or rain fall, and in some instances may furtherinclude other measurement data, such as temperature data sensed by thesensor unit 12. In one embodiment of determining in step 618 of whetherto inhibit irrigation, the controller 414 compares the measurement ofprecipitation and/or rainfall to some criteria, e.g., a stored thresholdlevel, to determine whether a predetermined relationship exits betweenthese variables (e.g., if the amount of measured rain fall exceeds athreshold level of rain). In some embodiments, the determination ofwhether the irrigation cycle should be inhibited comprises one or morecriteria, wherein the interface unit 14 and controller 414 processes thedata received from the interface unit to determine whether certaincriteria is met and based on this determination the interface unit maygenerate an interrupt message inhibit irrigation. In one embodiment, forexample, the interface unit 14 uses the information received from thesensor unit to determine a rate of change of the received atmosphericmeasurements, the interface unit may then generate an interrupt messageto inhibit irrigation when it senses a certain level of change in thereceived measurements, e.g., a positive rate of change in amount ofprecipitation or the rate of change of temperature, and/or other suchdata. In some embodiments, the instruction set operating in theinterface unit 14 is calibrated to correlate the information receivedfrom the sensor unit 12 to a level of rainfall that may be related tothe threshold level or other criteria. For example, in embodiments wherethe signal received at the interface unit 14 represents a raw electricalsignal output from the sensor unit 12, the transceiver 412, thecontroller 414 and/or other intermediate device processes this signal tocorrelate this signal to a corresponding level of rain fall.Alternatively, this correlation may be performed by the sensor unit 12,and the resulting correlation is forwarded to the interface unit 14. Insome embodiments, when the rain fall relationship does not exist thecontroller 414 may further compare other parameters, such as thereceived measurement of temperature to a stored temperature thresholdlevel to determine whether a predetermined relationship between thesevariables exists (e.g., if the measured temperature is below a thresholdtemperature). In other embodiments, the determination of whether arelationship exists between the measured rain level and a presetthreshold, or whether other variables such as temperature exceed apreset threshold, is made at the sensor unit 12 and the signal receivedby the interface 14 from the sensor unit 12 provides thesedeterminations from which the controller 414 determines whether toinhibit irrigation.

Once the controller 414 determines that irrigation should be inhibitedin step 618 (e.g., the threshold level of rainfall has been exceeded bythe amount of sensed or measured rain fall or the threshold level oftemperature is above the measured ambient temperature), the process 610continues to step 620 where the controller 414 generates an interruptsignal. In some forms, a relay device which is normally closed isopened, interrupting irrigation. In some embodiments, the relay deviceis implemented as a switching device which is opened to inhibit theirrigation. In step 622 when irrigation is being commanded by theirrigation controller 30 while the interface unit 14 is commanding thatirrigation be inhibited, a voltage sensor 422 monitors the voltageacross the relay contacts. In step 624, it is determined whether theirrigation cycle has terminated. When the irrigation cycle has notterminated, the process 610 returns to step 622 to monitor theirrigation cycle. When the irrigation cycle has terminated, the processmoves to step 626 where the interface unit 14 closes the relay device.Following step 626 the process returns to step 612 where the interfaceunit determines whether an irrigation cycle is initiated (e.g., thecurrent sensor device 420 monitors the current flow to determine if anirrigation cycle is detected).

Returning to step 618, when it is determined that irrigation should notbe inhibited, the system returns to step 612 to determine whether anirrigation cycle is detected. In some embodiments, the determinationthat irrigation should be inhibited (e.g., that a relationship existsbetween the measured variables and the thresholds) is made at the sensorunit 12, and upon transmitting a request to the sensor unit, theinterface unit 14 will receive an “irrigate” or “inhibit” command.

In some embodiments, when it is determined in step 618 that theirrigation is not to be interrupted (e.g., the level of rain fall orambient temperature do not meet the predetermined relationship),optional step 630 is entered where the interface unit determines whetherthe level(s) of the measurement data (e.g., rain fall, temperatureand/or other data) are such that the irrigation should be adjusted. Thismay be done by comparing the precipitation data and/or the temperatureto a second set of thresholds. Additionally or alternatively, theinterface unit 14 may forward one or more of the measurement data to theirrigation controller 30 allowing the irrigation controller to determinewhether irrigation is to be adjusted.

When it is determined in step 630 that the irrigation is to be adjusted,step 632 is entered and the interface unit 14 adjusts the run time ofthe irrigation cycle and/or notifies the irrigation controller 30 thatthe runtime should be adjusted (e.g., by forwarding measurement levelsand/or adjustments to be implemented). When it is determined in step 630that adjustments are not to be made or following step 632 the process610 returns to step 612 to detect the start of an irrigation cycle.

Referring back to FIG. 4, the user input 424 allows a user to input andadjust the stored threshold level(s), enable or disable the sensor(s),and/or adjust other settings. Generically, in one embodiment, the userinput 424 comprises at least one selectable user input that allows theuser to make adjustments and/or selections. The user input 424 maycomprise one or more of buttons, switches, levers, rotating dials, etc.The user display 426 may indicate the operational status of theinterface unit 14, e.g., the display may indicate that the receiver unitis powered on, what threshold level is selected, if the receiver unit isin an irrigation interrupt state, etc., and/or the operational status ofsensor unit 12 such as the operational mode of the sensor unit. The userdisplay 326 may be one or more of a display screen, liquid crystaldisplay (LCD), touch screen display, lights, LEDs, and/or other relevantdisplays. In some, embodiments for example, the display comprises abacklit LCD, for example, which is capable of displaying alphanumericcharacters with 11-segment LCD digits. It is noted that although theinput/output unit 18 (whether wired or wireless) is illustrated as atransceiver (wired or wireless), in some embodiments the input/output 18may comprise a separate transmitter and receiver.

FIG. 7A is an illustration of some embodiments of the interface unit 14for use in the rain sensor system 10 of FIGS. 1 and 2. In thisembodiment, the user input 424 is embodied as including an ON/OFF switch712, an up button 714 and a down button 716. The user display 426 isembodied as a small display screen 718. The ON/OFF switch 712 turns thepower to the interface unit 14 on and off. The up and down buttons 714and 716 are used to set and adjust one or more threshold levels and/orother parameters and settings. These thresholds and/or parameter may beutilized and/or forwarded to the sensor unit 12 to adjust a remote rainsensor to different threshold levels at the sensor unit 12 of the rainsensor system 10, such as described in U.S. Pat. No. 6,570,109; however,the threshold level is set electronically and at the interface unit 14.For example, by pressing the buttons 714 and 716, the user switchesbetween multiple discrete levels of rain thresholds, e.g., a lowthreshold, a mid threshold and a high threshold. In other embodiments,the up and down buttons 714, 716 cause an up and down gradient or analogadjustment to the stored threshold level. The display 718 may beconfigured to indicate which threshold level the interface unit 14 iscurrently set, notify the user of battery strength or low battery,indicate if the interface unit 14 is in watering interrupt mode or not,and other such information. In some embodiments, the display screen 718is not included.

In other embodiments, such as shown in FIG. 7B, an additional selectionbutton 715 is provided that allows a user to select different adjustablefeatures or settings of the interface unit 14. For example, theselection button 715 provides different adjustment functionality tobuttons 714 and 716. The display 718 indicates what parameter or settingthe user may adjust with buttons 714 and 716. For example, by repeatedlypressing the selection or menu button 715, the user may navigate betweendifferent selectable or adjustable settings or features. For example, asdescribed above, the selection button 715 allows the user to makeadjustments to the rain fall threshold level. Pressing the button 715again may allow the user to change the rain delay period after the waterthreshold has been exceeded and returned back below the threshold, tochange the temperature threshold level, and/or change other parametersor settings. The button 715 may also allow features to be turned on oroff with the buttons 714 and 716. For example, button 714 may be used toturn a feature selected by button 715 on, while button 716 turns thatfeature off.

Referring to FIG. 8, in some embodiments of the interface unit 14, thethreshold level is set by moving a multi-position switch 812 or othertype of drag bar between multiple positions. Each switch positionelectrically signals to the processor what threshold level correspondsto the proper switch position. In many embodiments, precipitationamounts between, for example, ⅛″ to ¾″ are selectable in discreteincrements or continuous manner. Further, in some embodiments, the userinput 424 comprises a three-position toggle switch 814 to allow the userto configure the unit for the desired operation. The switch 814 has acenter, left and right position. In some embodiments, placing the switchinto the center position places the interface unit 14 into a normaloperational mode where irrigation is inhibited if sufficientprecipitation has been detected by the sensor unit 12. Placing theswitch into the left position places the interface unit 14 into a bypassmode where irrigation is not inhibited by the system. The setting theswitch into the right position places the interface unit 14 into a testmode. In some embodiments, the right position is a spring-loaded returnto center, automatically releasing to center position e.g., normal mode,when the switch is no longer held in position. The user display 426, insome embodiments, may include an LCD backlit display screen 816. In manyembodiments, the user input 424 may further include a pushbutton switch820 to allow the user to activate the LCD backlight for a period oftime.

FIG. 29A is an illustration of alternate embodiment of the interfaceunit 14. This embodiment comprises for example an LCD touch screenembodying both user input and user display functionality. In otherembodiments, the user input may comprise selectable buttons, dialsand/or switches, and the user display may be a graphical display and/orother means of displaying data to the user. The user input 424 isembodied as including a rain threshold selector 2936, a temperaturethreshold selector 2926, rain sensor activation selector 2932 andtemperature activation selector 2930. The rain threshold selector 2936and temperature threshold selector 2926 enable the user to set or adjustthe threshold level for the amount of rain or temperature respectively.These thresholds may be utilized at the interface unit 14 for makingdecisions regarding whether to inhibit/interrupt or permit/allowirrigation, and/or may be forwarded to the sensor unit 12 to adjust aremote rain sensor to different threshold levels at the sensor unit 12.The rain activation selector 2932 and the temperature activationselector 2930 further allow the user to adjust the mode of operationwherein the user may select to inhibit irrigation based on the amount ofrain or precipitation and/or the temperature. For example, using theselectors 2930 and 2932 the user may chose to interrupt irrigation basedon both precipitation and temperature data by activating both selectorand/or one or neither of the measurements by deactivating either or bothof the selectors 2930 and 2932. It is noted that the rain thresholdselector 2936 and the temperature threshold selector 2926 may begenerically referred to as selectable inputs that allows a user toadjust a respective threshold level.

The display 2900, as illustrated in FIG. 29A, is embodied as aconnectivity indicator 2938, a signal strength indicator 2920, aconnection indicator 2924, a rain indicator 2934, a battery strengthindicator 2922, a temperature indicator 2928, and a system statusindicator 2940. The connectivity indicator 2938 indicates whether thereis a connection between the interface unit 12 and the sensor unit 14.The signal strength indicator 2920 displays the signal strength of thewireless connection between the sensor unit 12 and the interface unit14, where the number of bars represents the strength of the signalsreceived from the sensor unit 12 at the interface unit 14. Theconnection indicator 2924 displays the number of sensors 12 currentlyconnected to the interface unit 14 and further displays which of thesensors 12 a-n is currently able to communicate with the interface unit.For example, two sensor units are illustrated, the upper left one inactive communication with the interface unit, while the lower left oneis not connected to the interface unit. The rain fall indicator 2934 andthe temperature indicator 2928 display the amount of rain fall and thetemperature currently present at the sensor unit 12 relative to thethresholds (indicated by 2936 and 2926). The signal strength indicator2920 displays the signal strength between the interface unit 14 and thesensor unit 12. The battery strength indicator 2922 may display thebattery strength of the battery at the interface unit, sensor unit,and/or the rain sensor system 10 as a whole. For example, in oneembodiment, the battery strength indicator displays the battery strengthmeasurement that it receives from the sensor unit. The system statusindicator 2940 displays the mode of operation, i.e., whether the systeminhibits irrigation based on rain fall, temperature, and/or both, andadditionally displays whether irrigation is inhibited currently.

As illustrated in FIG. 29A, the top section of the system statusindicator 2940 indicates whether the system is controlling irrigationbased on the measurement of rain, temperature, or both. For example,FIG. 29A shows the system status indicator displaying that the system iscurrently only inhibiting based on the amount of rain, i.e., only therain symbol is present at the top of the indicator. The system statusindicator further indicates whether the system is currently interruptingirrigation, where the sprinkler symbol on the indictor is either showingirrigation or displays that no irrigation is occurring, for example, thesystem status indicator as illustrated in FIG. 29A indicates thatirrigation is currently not interrupted since the sprinkler symbol isshowing irrigation.

FIG. 29B illustrates an alternative embodiment 2901 of the display 2900of the interface unit 14 for use with the system 10, for example inembodiments when the interface unit 14 is coupled with multiple sensorunits. As illustrated, in some embodiments the connection indictor 2924displays the interface unit, and also displays multiple sensor unitscoupled to the interface unit (in this case sensor units 1, 2, 3 and 4).The interface unit also displays the battery strength and signalstrength 2920, and battery strength 2922 for each of the sensor units12.

With respect to the embodiments of FIGS. 7A, 7B, 8, 29A and 29B andothers described herein, prevention of tampering of slide switchesand/or push buttons may be provided by using a mechanical cover (notshown) over the switches/buttons. Additionally or alternatively, in someembodiments, buttons have to be pressed and held for a period of time(e.g., 2-5 seconds) before any changes occurs. This prevents theaccidental altering of receiver unit settings.

The interface unit 14 may be powered by connection to the controller 30,e.g., it draws power from the 24 VAC power source of the controller 30.In other embodiments, battery, solar, wind powered or other powersources and/or combinations of sources may be used to supply power tothe interface unit 14.

In some embodiments, the sensor unit 12 includes an indicator light,such as a bi-color LED, that is visible to a user and also includes thedriver circuitry and power to drive the indicator light. This indicatorlight is useful when initializing the sensor unit 12 and/or theinterface unit 14. For example, in some embodiments, the interface unit14 includes a test mode button that when pressed sends a signal to thesensor unit 12. In one embodiment, when the sensor unit 12 receives thesignal, it illuminates the indicator light. An installer may mount thesensor unit 12 to a given location. The test button on the interfaceunit may be activated allowing the installer to return to the sensorunit to verify that the indicator light is illuminated, verifying thatthe communication between the sensor unit 12 and the interface unit 14is valid.

In some embodiments, additionally or alternatively, when the sensor unitreceives the signal from the interface unit it determines the signalstrength of the signal and displays the signal via the indicator light.For example, in one embodiment the indicator light blinks a certainnumber of times representing the signal strength of the test signal. Aninstaller may use the signal strength indication to locate one of aplurality of possible installation locations with the best signalstrength. Additionally, in some embodiments the installer may move thesensor unit where the signal strength varies with the change inlocation, and further where the determining and displaying of the signalstrength is done automatically, so that the installer may install theinterface unit, push the test message and then move the sensor unit inthe remote location until the installer finds a location with the bestsignal strength where the sensor unit 12 may be installed.

Additionally and/or alternatively, once power is applied to theinterface unit 14, the interface unit starts sending signals to thesensor unit 12 for a period of time. If the sensor unit 12 is in range,the indicator light is illuminated. For example, an installer maydetermine whether the location of the sensor unit 12 is adequate and/orin communication with the interface unit 14 based on the decisioncriteria of whether the bi-color LED is illuminated (e.g., illuminatedgreen). If the location is determined to be inadequate, the bi-color LEDis not illuminated or is illuminated a second color (e.g., illuminatedred).

FIG. 9 illustrates a flow chart of the process 900 by which theinterface unit communicates with the sensor unit once communication isestablished between the interface unit 14 and the sensor unit 12,according to some embodiments of the rain sensor system 10 illustratedin FIGS. 1 and 2. In some embodiments, the process 900 initiates at step910 where a determination is made as to whether there is a sensor unit14 to receive an activation and/or start up message from the interfaceunit. This determination may include retrieving from memory 418identification information for one or more sensor units 12 with whichthe interface unit is associated. Step 910 may be an optional step. Forexample, when there is only a single sensor unit 12 that is associatedwith the interface unit. Additionally or alternatively, the interfaceunit may instead skip to step 912 and broadcast a request as describedbelow to each sensor unit associated with the interface unit 14. Thisidentification information may include the version number of the sensorunit, an identification number of the sensor unit and/or otherinformation uniquely assigned to the sensor unit. Further, thisinformation, in some instances, is stored in the memory 418 at the timethe sensor unit 12 is installed, or assigned to an interface unit 14. Ifthere are no sensor units associated with the interface unit, theprocess 900 moves to step 920 where a message is displayed on the userdisplay 426 alerting the user that there are no sensor units 12associated with the interface unit 14.

In step 912, once power is applied to the interface unit 14 theinterface unit enters an initialization mode and transmits a request toone or more sensor units 12. In step 914, the interface unit 14 checksto see if an acknowledgment message is received from the sensor unit 12.When an acknowledgment is received in step 914 the process thencontinues to step 916, where the interface unit 14 processes the messageand displays the appropriate data on the display 426 (e.g., aconfirmation of connection message, an identification of the one or moresensors from which responses are received and/or other suchinformation). When the sensor unit 12 is in range, as introduced above,the indicator light may also be illuminated at the sensor unit.

If it is determined in step 914 that an acknowledgment is not received,the process continues to step 918 where an incremental counter isincreased by one, and it is determined whether the request signal hasbeen transmitted a predefined number of times. If the request has notbeen sent the predefined number of times, the process returns to step912 to again transmit the request. The subsequent transmission may bedelayed for a period of time and/or the subsequent request may betransmitted at a higher transmit power in attempts to connect with thesensor unit 12. Alternatively, when an acknowledgment is not receivedafter a predetermined number of connection attempts the processcontinues to step 920 where it displays a message alerting the user.

Following step 916, following the initialization mode, the interfaceunit 14 enters the normal or sleep mode. In normal mode the interfaceunit will function in accordance with the process as described in FIG.6. In many embodiments, the interface unit 14 also provides a test modeto enable the user to determine whether or not a proposed location forthe sensor unit will result in satisfactory signal reception andcommunications reliability. This is made possible, in such embodiments,by having a two way communication between the sensor and interface unit.In the test mode, the interface unit 14 initiates a test messagetransmitted to the sensor unit and receiving an acknowledgment to verifythat the sensor unit 12 and interface unit 14 may communicate. The testmode may be initiated automatically by the system in the initializationstep. In some embodiments, the user may also initiate a test mode byusing the user input 424.

In many embodiments message traffic between the interface unit 14 andsensor unit 12 occurs in pairs, e.g., when a message is sent, there isan acknowledgement. In the event that the sender of an initial messagedoes not receive an acknowledgement corresponding to the message sent,the originator of the message may assume that the message was lost andattempt to retransmit the message. FIG. 10 illustrates a process 1000that is implemented in the event that loss of communication occursbetween the sensor unit 12 and interface unit 14 of rain sensor deviceor system 10 illustrated in FIGS. 1 and 2. In step 1010 after sending amessage, the originator of the message, e.g., the sensor unit 12 or theinterface unit 14, determines whether an acknowledgment is received.When an acknowledgement is received, the process 1000 continues to step1050 to continue normal operations. Alternatively, if an acknowledgmentis not received, typically within a predefined period of time, then theprocess continues to step 1012 where the originator resends the message.

In step 1014 the originator checks to see if an acknowledgment isreceived. When it is determined in step 1014 that an acknowledgment isreceived, the process continues to step 1050 and resumes its normaloperation. If no acknowledgment is received then the process continuesto step 1016 to determine whether a predefined time limit forreattempting to send the message is reached and/or whether the messageis retransmitted a predefined number of times. When it is determined instep 1016 that the predefined time period and/or number of attempts isnot reached, the process returns to step 1012 to continue attempting totransmit the message. Alternatively, when, an acknowledgment is notreceived within the predetermined period of time and/or within thelimited number of attempts, the system continues onto step 1018 wherethe originator attempts to determine whether there is interference inthe communications channel.

In some embodiments, both the sensor unit 12 and interface unit 14periodically monitor the RSSI values obtained from the receiver and/ortransceiver 316, 412 during periods where no message traffic is beingpassed. These values are noted and stored in memory so that informationabout the noise levels at the sensor unit 12 and interface unit 14locations are available with which to assess the communications channelat a given time. In some embodiments, when no message traffic is beingpassed, the interface unit 14 samples the RSSI value randomly, atscheduled times, at intervals, e.g., at intervals of one minute, or thelike. Additionally or alternatively, the sensor unit 12 may samples theRSSI value, randomly, at scheduled times or at intervals, e.g., atintervals of one hour. In step 1018 the originator of the message maysamples the RSSI value, for example from its receiver chip, and assesseswhether or not there is interference or noise levels that exceed limits.When it is determined that high noise level is present the systemcontinues to step 1020 where the originator increases the transmittalpower.

In step 1022, the device attempts retransmission of the message at theincreased transmitter power. In some embodiments, this step comprisesretrieving the maximum transmittal power from memory. In step 1024 thesystem checks to see if an acknowledgment is received. When anacknowledgement is received, the process continues to step 1050 totransition to a normal mode of operation. If the retransmission attemptdoes not result in an acknowledgment, step 1026 is entered where it isdetermined whether the noise level has returned to or is below athreshold and/or a nominal value. In some embodiments, the process mayrepeat steps 1022 and 1024 in attempts to resend the message for acertain period of time or a predetermined number of attempts beforecontinuing to step 1026. When it is determined in step 1026 that thenoise level over the communication link has subsided or reduced todesired levels, the process returns to step 1012 to retransmit themessage. In some embodiments when returning to step 1012 the interfaceunit sends a message to reset the transmittal power of the sensor unit.

Alternatively, when it is determined in step 1026 that the noise levelhas not reduced, the originator device continues to sample RSSI values,e.g., at predetermine time intervals and the process then proceeds tostep 1030. In step 1030, it is determined whether a period of time haselapsed without detecting a reduction in noise level (e.g., reduction toa desired level). If the time limit has not elapsed the process returnsto step 1026 to determine whether there has been a reduction in noiseover the channel. Alternatively, when the time period has elapsed, theprocess enters step 1032 where an error message is displayed and/orotherwise indicated and the process terminates. In some embodiments,during this process the user display 426 of the interface unit 14displays status information, such as a noise message or levels, errormessage, acknowledgement not received and/or other such information.

Returning to step 1018, when it is determined that the noise level isnot in excess, it is presumed that the receiving device at the other endof the communication channel (e.g., wireless link) has failed. Thesystem then continues to step 1040 where the transmitting deviceattempts to reestablish communication. In step 1042, it is determinedwhether an acknowledgement is received for the reconnection. When thereconnection is achieved, the process 1000 returns to step 1012 toresend the message (or in some instances to step 1050 for normaloperation). Alternatively, the process continues to step 1044, where itis determined whether a time limit has expired while attempting toreestablish communication. When the time limit has not been reached theprocess returns to step 1040. When the time limit has been reached, theprocess continues to step 1032, and an error message is displayed and/orotherwise indicated and the process terminates.

In some embodiments, the sensor unit 12 in performing steps 1016, 1030and/or 1044 may attempt implement a shorter amount of time and/or numberof tries before ceasing to transmit, and waits until the interface unit14 attempts to reconnect. Additionally or alternatively, the sensor unit12 may not perform all of the steps of the process 1000, and maytermination communication earlier in the process to await communicationfrom the interface unit 14. In some embodiments, the user display 426 ofthe interface unit 14 displays a NO SIGNAL message or other indicatorduring the time the interface unit is waiting for an acknowledgementand/or is attempting to reconnect until reconnection is achieved or theprocess terminates.

The next several figures illustrate and describe various types ofsensors and circuitry for sensing or generating a signal indicative ofthe amount of rain fall. These drawings have been simplified and do notillustrate all components of the device. For example, all components ofthe circuitry and outputs such as a power source (battery and/or solarcell) and wireless transmitters are not illustrated. Depending on theembodiment, a signal representing a sensed value that corresponds to anamount of rain fall received is transmitted to the interface unit 14. Insome forms, the interface unit is configured to properly interpret theinformation in the signal and correlate that information to acorresponding level of rain fall received. In other embodiments, thesignal is converted to a corresponding level of rain fall prior to beingtransmitted to the interface unit 14. Still further in someimplementations, the sensor unit 12 determines whether a threshold levelof rain is received and transmits an indication of whether the thresholdis exceeded in response to an inquiry from the interface unit 14.

Referring next to FIG. 11, a diagram is shown of a sensor unit 1102 foruse in a system to interrupt execution of one or more watering schedulesof an irrigation controller according to several embodiments. In thisembodiment, the sensor unit 1102 includes a housing 1104 having anopening 1106 to allow rain fall to enter a volume 1108. Although notillustrated, a ceramic or other porous filter is located in the opening1106 to allow rainfall to be received into the volume 1108 whilepreventing dirt and other debris from entering the volume. Within thevolume 1108 is a moisture absorptive material that expands and contractsbased on the presence of and absence of rain fall, such as a hygroscopicmaterial 1110 comprising a plurality of hygroscopic discs. It isunderstood that the shape and configuration of the hygroscopic materialmay vary according to the specific implementation. For example, thehygroscopic material 1110 may comprise discs (as illustrated, or maycomprise other suitable materials, such as an expandable granularmaterial (e.g., polyacrylamide, etc.) contained within an envelope orflexible container.

The material 1110 expands in the presence of water, expanding further asthe presence of water increases, and contracting as water is evaporatedfrom the volume 1108. Vents (not illustrated) are provided to allowevaporation, i.e., allow the volume 1108 to dry when rainfall is notpresent. A plunger 1112 is coupled to the material 1110 and a spring1114 to bias the material 1110 upwardly. A metal piece 1116 (e.g., ametal plate or short section of metal cylindrical tubing) is mounted onthe lower surface of the mechanical plunger 1112. This metal piece 1116is situated in proximity to a capacitor 1118 mounted on the printedcircuit board 1120 comprising the sensor electronics. In someembodiments, the printed circuit board 1120 may comprise a controller,memory, transceiver and/or other relevant elements. The capacitor 1118forms the capacitive arm of an oscillator. The capacitor 1118 is suchthat the electric field surrounding its plates should have sufficientextent so that the metal piece 1116 mounted on the plunger 1112 willaffect its capacitance. Expansion of the hygroscopic material 1110causes the spacing between the piece of metal 1116 and the capacitor1118 to change, altering the capacitance of the plunger/capacitorsystem. Changes in the capacitance of the system will result in a changeof the frequency of oscillation of the oscillator, the frequency ofcorresponding to the amount of precipitation. The sensed frequencyprovides an analog continuous measurement corresponding to the amount ofrain fall. The value of this sensed frequency is transmitted to theinterface unit for a determination of whether a rain threshold has beenexceeded. Additionally or alternatively in some embodiments, the rainsensor unit 1102 detects when a threshold amount of water is received.For example, contact of the piece of metal 1116 with the capacitor 1118or circuit board 1120 causes the closing of a switch indicating that athreshold amount of water has been exceeded such that a signalindicating that the threshold has been exceeded is then forwarded to theinterface unit in response to the request from the interface unit. Inanother embodiment, item 1118 is a mechanical switch or button that whencontacted by item 1116, presses the switch. In this embodiment, the factthat the switch is pressed, closed or contacted indicates to theelectronics that the threshold has been exceeded.

Referring next to FIG. 12, a sensor unit 1202 includes a strain gauge1204 coupled to the printed circuit board 1120 and that engages theplunger 1112 when the material 1110 expands. Expansion of the material1110 changes the force applied to the strain gauge 1204 by the plunger1112. The plunger 1112 may initially contact the strain gauge 1204 ornot and a spring 1114 may optionally be included between the straingauge 1204 and the plunger 1112. This change in force on the straingauge 1204 is detected by appropriate electronics on the printed circuitboard 1120. The sensed force provides an analog continuous measurementcorresponding to the amount of rain fall. The value of this sensed forceis transmitted to the interface unit 14 for a determination of whether arain threshold has been exceeded and/or a determination of whether athreshold is exceeded may be transmitted to the interface unit 14.

Referring next to FIG. 13, a sensor unit 1302 includes an inductor 1304wrapping around the material 1110 and coupled to the printed circuitboard 1120. The inductor 1304 is fabricated from a fine wire and formsone arm of an oscillator circuit on the circuit board 1120. Expansion ofthe hygroscopic discs (material 1110) changes the inductance andinternal dissipation of the inductor, changing the frequency andamplitude of the oscillator. This change is detected by appropriateelectronics on the printed circuit board 1120, providing an analogcontinuous measurement corresponding to the amount of rain fall and/oran indication of exceeding a threshold. The value of this sensedfrequency and/or amplitude is transmitted to the interface unit 14 for adetermination of whether a rain threshold has been exceeded.

Referring next to FIG. 14, a sensor unit 1402 includes graphite stackresistor 1404 coupled to the printed circuit board 1120 and that engagesthe plunger 1112 when the material 1110 expands. Expansion of thehygroscopic discs (material 1110) changes the force applied to thegraphite stack resistor 1404 by the plunger 1112. The plunger 1112 mayinitially contact the stack resistor 1404 or not and a spring 1114 mayoptionally be included between the stack resistor 1404 and the plunger1112. This change in force on the graphite stack 1404 changes itselectrical resistance, and is detected by appropriate electronics on theprinted circuit board 1120, providing an analog continuous measurementcorresponding to the amount of rain fall. The value of this sensedresistance is transmitted to the interface unit 14 for a determinationof whether a rain threshold has been exceeded.

Referring next to FIG. 15, a sensor unit 1502 includes a magnet 1504 ona surface of the mechanical plunger 1112. This magnet 1504 is situatedin close proximity to a Hall Effect device 1506 mounted on the printedcircuit board 1120 comprising the circuitry or electronics of the sensorunit 1112. Expansion of the hygroscopic discs (material 1110) causes thespacing between the magnet 1504 and the Hall Effect device 1506 tochange, changing the output of the Hall Effect device 1506. This changein the output of the Hall effect device 1506 is detected by appropriateelectronics on the printed circuit board 1120, providing an analogcontinuous measurement corresponding to the amount of rain fall. Thevalue of this output is transmitted to the interface unit 14 for adetermination of whether a rain threshold has been exceeded.

Referring next to FIG. 16, a sensor unit 1602 is shown in which the baseof the mechanical plunger 1112 is in contact with a wiper 1604 of afixed resistive sensing element 1606. In some embodiments, the resistiveelement and the wiper form a linear potentiometer. Expansion of thehygroscopic discs (material 1110) changes the position of the linearwiper 1604 on the potentiometer 1606, changing its resistance. Thischange in resistance is detected by appropriate electronics on theprinted circuit board 1120, providing an analog continuous measurementcorresponding to the amount of rain fall. The value of this resistanceis transmitted to the interface unit 14 for a determination of whether arain threshold has been exceeded.

Referring next to FIG. 17, a sensor unit 1702 is shown which does notuse a hygroscopic material, and instead uses a capacitor 1704 includinga set of plates or electrodes. In the illustrated form, the electrodesare formed as coaxially aligned cylindrical tube electrodes 1706 and1708, electrode 1706 being the outer coaxial tube and electrode 1708being the inner coaxial tube. These tubes are illustrated in crosssection view. The capacitor 1702 forms the capacitive arm of anoscillator implemented on the circuit board 1120. The volume 1108 andelectrodes 1706 and 1708 are configured such that water collects in thespace between the electrodes 1706, 1708, changing the capacitance of thecoaxial system. The high dielectric constant of water will effect alarge change in the capacitance of the system under conditions of smallaccumulations of precipitation. Changes in the capacitance of the systemwill result in a change of the frequency of oscillation, providing ananalog continuous measurement corresponding to the amount of rain fall.The value of this changing frequency is transmitted to the interfaceunit 14 for a determination of whether a rain threshold has beenexceeded.

Referring next to FIG. 18, a sensor unit 1802 is shown which does notuse a hygroscopic material. In this embodiment, a material whoseelectrical resistance changes when exposed to water is employed todetect precipitation. As illustrated, a resistance cell 1804 is locatedwithin the volume 1108. Electrodes 1806 and 1808 couple from theresistance cell 1804 to the circuit board 1120 and measure theresistance across the cell. Resistance across the resistance cell 1804decreases as it becomes wet relative to the initial readings when thesensor unit is initialized. Changes in the resistance of the cell 1804correspond to changes in the level of rain fall received, providing ananalog continuous measurement corresponding to the amount of rain fall.The value of this changing resistance is transmitted to the interfaceunit 14 for a determination of whether a rain threshold has beenexceeded.

Referring next to FIG. 19, a sensor unit 1902 is shown in which the baseof the mechanical plunger 1112 is in contact with a ferrous plunger1906. This plunger 1906 is situated such that it moves within aninductive coil 1908 connected to the printed circuit board 1120. Theinductor 1908 is fabricated from a fine wire and forms one arm of anoscillator circuit on the circuit board 1120. Expansion of thehygroscopic discs (material 1110) changes the position of the plunger1906 altering the inductance of the plunger/inductor system. Changes inthe inductance of the system will result in a change of the frequency ofoscillation of the oscillator. This frequency change is detected byappropriate electronics on the printed circuit board 1120, providing ananalog continuous measurement corresponding to the amount of rain fall.The value of this frequency is transmitted to the interface unit 14 fora determination of whether a rain threshold has been exceeded.

Referring next to FIGS. 27A and 27B, a sensor unit 2700 is shown inwhich the mechanical plunger 1112 is in contact with the wiper 1604 ofthe fixed resistive sensing element 1606. As illustrated in FIG. 27B, inone embodiment a spring 2712 is coupled to the wiper 1604 and theplunger 1112 pushes the wiper towards the resistive sensing materialmaintaining appropriate contact between the resistive sensing materialand the wiper. In some embodiments the wiper and the resistive sensingelement are parts of a linear potentiometer. Expansion of thehygroscopic discs (material 1110) changes the position of the linearwiper 1604 on the resistive sensing element 1606, changing itsresistance. In some embodiments, this change in resistance is detectedby appropriate electronics on the printed circuit board 1120, where itis processed to generate an indication representing an amount of rainfall. For example, in one embodiment, the processing results in ananalog continuous measurement corresponding to the amount of rain fall.The indication representing the amount of rain fall derived from thisresistance is transmitted to the interface unit 14 for a determinationof whether irrigation should be permitted or interrupted. In someembodiments, the indication may also be used by the sensor unit todetermine whether some internal criteria are met, for example, whenchanging the mode of operation of the sensor unit. In someimplementations, the sensor unit also includes an antenna 2704, a lightindicator 2706 and a temperature sensor 2708 coupled to the printedcircuit board. Further, in some embodiments, the sensor unit comprises abattery housing 2710 which holds the batteries from which the sensorunit draws its power.

According to several embodiments, the wiper 1604 can be genericallyreferred to as a first element, while the resistive sensing element 1606may be generically referred to as a second element. In a preferredembodiment, the first element is a moving element and the second elementis fixed in a location. Generically, the plunger causes the firstelement to move relative to the second element causing a change in avariable (in this case, an electrical resistance) corresponding to anamount of rain fall. In some embodiments, the controller implemented onthe circuit board is measures the variable and generates signalscomprising an indication of the amount of rain fall based on themeasured variable.

Referring next to FIG. 28, a sensor unit 2800 is shown in which themechanical plunger 1112 is in contact with a first electrode 2804 (e.g.,an electrode plate). In response to expansion/contraction of thehygroscopic disks, the moving plunger moves the first electrode 2804relative to a second electrode 2808 (e.g., an electrode plate) fixed tothe electronic circuit board 1120. The fixed second electrode 2808 iscovered with a layer of insulator material 2806, e.g., Mylar insulation,where the insulator material is in contact with the moving firstelectrode 2804 such that it maintains a gap between the fixed electrode2808 and the moving electrode 2804. As illustrated in FIG. 8, in oneembodiment, a spring 2810 coupled to the fixed electrode 2804 and theplunger 1112 pushes the moving electrode 2804 towards the fixedelectrode 2808 and the insulator material maintaining appropriatecontact between the fixed electrode covered with the insulator materialand the moving electrode. Expansion of the hygroscopic discs (moistureabsorptive material 1110) changes the position of the moving electrode2804 relative to the fixed electrode 2808, changing the surface area ofthe fixed electrode 2808 that is covered by the moving electrode 2804.Accordingly, this changes the capacitance generated between the twoelectrodes given a voltage difference therebetween. For example, avoltage is applied to the fixed electrode. In some embodiments, thischange in capacitance is detected by appropriate electronics on theprinted circuit board 1120, where it is processed to generate anindication representing an amount of rain fall. For example, in oneembodiment, the processing results in an analog continuous measurementcorresponding to the amount of rain fall. The indication representingthe amount of rain fall derived from this capacitance is transmitted tothe interface unit 14 for a determination of whether irrigation shouldbe permitted or interrupted. In some embodiments, the indication mayalso be used by the sensor unit to determine whether some internalcriteria are met, for example, when changing the mode of operation ofthe sensor unit.

According to several embodiments, the first electrode 1804 can begenerically referred to as a first element, while the second electrode1808 may be generically referred to as a second element. In a preferredembodiment, the first element is a moving element and the second elementis fixed in a location. Generically, the plunger causes the firstelement to move relative to the second element causing a change in avariable (in this case, an electrical capacitance due to a changingsurface area of the first element positioned above the second element)corresponding to an amount of rain fall. In some embodiments, thecontroller implemented on the circuit board is measures the variable andgenerates signals comprising an indication of the amount of rain fallbased on the measured variable.

In many embodiments, the rain sensor system 10 is capable of measuringrainfall and according to one or more selected settings to permit orprevent an irrigation controller 30 from irrigating. Rainfall settingsare, for example, from ⅛″ to ¾″ and are selectable at the interface unit14. The rain sensor system 10 comprises the remote sensor unit 12, andan interface unit 14 mounted near an irrigation controller 30.Communication between the remote sensor unit 12 and interface unit 14,according to some embodiments, is a two way wireless radio link that mayeliminate the need to route wires/cable between the units. The wirelesssensor unit 12 may be in one of the following forms or a combinationsthereof, a wireless rain sensor (transmitter/receiver combination pack),a wireless rain/freeze sensor (transmitter/receiver combination pack), awireless rain sensor receiver, a wireless rain/freeze sensortransmitter, and/or a wireless rain/freeze sensor receiver.

FIG. 31 illustrates one possible implementation of the overall operationof the system 10 according to several embodiments. In step 3112 thesensor unit 12 generates an indication of the amount of rain and/orother data such as temperature. In one embodiment, the rain sensorgenerates such data periodically e.g. every 5 minutes. In otherembodiments, the sensor unit may generate such indications in responseto a request from the interface unit 14. Next, in step 3114 the sensorunit transmits a signal comprising at least the generated indication tothe interface unit 14. In some embodiments, the sensor unit may initiatetransmission to the interface unit 14 once it detects a change in someatmospheric parameters, e.g., amount of rain fall and/or temperature,and sends an update message to the interface unit. Additionally oralternatively, the sensor unit 12 may transmit the indication to theinterface unit 14 at fixed intervals, e.g. every 6 hours. The sensorunit may also transmit the indication to the interface unit 14 inresponse to a request from the interface unit 14. In one embodiment, themessage may include the sensed amount of rain fall, sensed temperature,battery strength, signal strength and/or other data available at thesensor unit.

In step 3116, the interface unit 14 receives the signal containing thedata from the sensor unit. In step 3118, the signal is processed toobtain the indication of data from the sensor unit, such as amount ofrain or precipitation, and/or temperature. Next, in step 3120 theinterface unit 14 determines whether a relationship exists between theindications and a threshold and/or other criteria. If in step 3120 theinterface unit 14 determines that the relationship exists, then in step3122 the interface unit generates an interrupt command to causeirrigation executed by an irrigation controller to be interrupted.Alternatively, when the interface unit 14 determines that therelationship does not exist, the interface unit 14 does not take anyactions and returns to step 3116. Thus, in this way, the interface unitallows or permits irrigation executed by the irrigation controller tooccur. In some embodiments, steps 3118 and 3120 may be generically bereferred to as the step of determining, based at least on the indicationfrom the signal, whether irrigation should be interrupted.

The interface unit 14 typically is mounted on a wall near to, and wiredto, an irrigation controller 30. The interface unit may include methodsfor outdoor and/or indoor mounting. For example, a mounting plate may beprovided to be secured into position with one or more screws. Theinterface unit 14 then slips and/or otherwise is connected onto themounting plate. Further, the interface unit 14 typically includes ahousing. The housing may be made of plastic and may include means tosecure the device to a wall without the mounting plate (e.g., a pair ofkeyhole slots). The housing may be made of polymetric material. It isdesired that if the external housing is of a polymetric material, itmeets UL standards for flammability, UL 94-5V or better, UV resistance,water absorption, and other applicable UL safety standards. The housingis set up for outdoor/indoor mounting.

An installation mode is activated in the interface unit 14 that thesensor unit 12 unit responds to by displaying the signal strengthreceived from the interface unit. The sensor unit 12 may be mounted withone or more attached brackets in a location that indicates good signaland that catches direct rainfall. The mounting bracket employed by thesensor unit 12 is designed so that a minimum number of tools are neededfor installation. The material employed for this bracket is light inweight and resistant to corrosion from water and sunlight.

After installation a simple signal test may be performed to verifycommunication is working properly between the sensor unit 12 and theinterface unit 14. In some embodiments, the sensor unit 12 has batteriesthat last for 5 years or more under the following conditions: one (1)“TEST” mode activation per year for the duration of five minutes and atotal of ten (10) one-second transmissions per day at a power level of+10 dBm. According to many implementations, the system does not requireend-user calibration. Normal maintenance consists of debris removal,elimination of plant encroachment, and periodic battery replacement.

The rain sensor unit 10 is used in conjunction with 24 VAC irrigationcontrollers 30 to conserve water usage by automatically preventing theirrigation controller from irrigating once the rainfall reaches apre-set level.

In some embodiments, the interface unit 14 operates by receivingperiodic communication from the sensor unit and processing the datareceived to decide whether or not to irrigate based on internal rulesincluding, for example, past history, rate of rainfall, thresholds,and/or other criteria. Additionally or alternatively, in someembodiments, the interface unit 14 may operate by interrogating thesensor unit 12 and then deciding to water or not water based on internalrules including past history. In some situations, for example, thesensor unit 12 will show dry conditions and the interface unit 14 willnot allow watering due to recent rainfall. Watering may be prevented bybreaking the continuity of the common circuit or connecting to thesensor input of the irrigation system, which prevents the solenoidvalves of the irrigation system from operating.

In some embodiments, the system operates in either the 868 MHz or 915MHz license-free ISM bands. It is understood other embodiments willoperate in other frequency bands, for example, some embodiments operateat 2.4 GHz and others operate in the 400 MHz ISM band. The systemoperates reliably at a straight-line distance of 300 feet or more withthe sensor unit 12 installed ten feet above the ground and the interfaceunit 14 installed five feet above the ground.

In one example implementation of the rain sensor device or system 10,communications reliability is defined as a message reception rate of 99%or more between the sensor unit 12 and the interface unit 14 while thesystem is situated in a residential environment with buildings, treesand other obstructions. This 99% reliability performance metric is withrespect to an environment where Rayleigh fading is present, having alink budget fading margin of 20 dB.

In the 915 MHz band the received signal strength profile that is used toapproximate the propagation environment over communication distancesless than the breakpoint distance is graphically illustrated in FIG. 20,with the breakpoint distance defined as

$\frac{4h_{TX}h_{RX}}{\lambda}$

where h_(TX) is the transmitter height above ground, h_(RX) is thereceiver height above ground, and λ is wavelength. For the 868 MHz band,the received signal strength profile used is graphically illustrated inFIG. 21.

The sensor unit 12 and interface unit 14 may each employ a low-cost,single chip radio transceiver device that is capable of operating acrossthe 868 MHz and/or 915 MHz ISM bands without requiring tuning orcomponent changes. The transceiver devices 316, 412 are capable ofgenerating either direct sequence or frequency hopping spread spectrumsignals. In some embodiments, it is desired that the transceiver devicemeets UL 1950 safety standard and CSA C22.2. In one embodiment, thedevices may have a maximum transmitted power level of 10 milliwatts (+10dBm) or more into a 50Ω resistive load. The frequency of operation andtransmitted power level are adjustable through firmware. The device iscapable of achieving compliance with all applicable FCC regulations forunintentional and intentional radiators in the 868 MHz and/or 915 MHzbands. In some embodiments, the transceiver 412 may be implemented as asingle-chip transceiver 412 employed on the sensor unit 12 providing ananalog and/or digital Received Signal Strength Indicator (RSSI) outputsignal. In one embodiment where the RSSI output is an analog signal, itis provided to one channel of the microcontroller's ADC.

In many embodiments, the sensor unit 12 operates from a high capacitylithium-ion battery. It may employ power conservation techniques toprovide a battery lifetime of five years or more while meeting its otherfunctional operating capabilities. A voltage sensing or other batterymonitor circuit such as battery voltage sensor 320 is employed, in someembodiments, to measure the battery voltage while it is under load.According to some implementations, the output voltage signal of thismonitor circuit is provided to one channel of the microcontroller's ADC326.

In some embodiments, the sensor unit 12 may include an adjustablecap/collector, and a micro sensor on the PWB protected by a waterproofseal that measures rainfall total.

According to some implementations, the sensor unit 12 utilizes alow-cost 8-bit microcontroller 312 that has sufficient computationalpower and speed to support the functional capabilities of the unit. Itis equipped with one or more very low power “sleep” modes capable ofbeing terminated by externally and/or internally-generated interruptevents. The microcontroller or microprocessor may employ a quartzcrystal for generation of an internal clock signal.

In some embodiments, the microcontroller 312 additionally employs FLASHmemory for storage of executable firmware, and is capable of beingprogrammed “in-system”. An in-system programming port may be availableon the printed circuit board for accomplishing the programming processduring final assembly. The in-system programming port may be accessiblevia surface pads (through the use of “pogo” pins on an ICT fixture). Aprogramming header may also be available on the printed circuit board topermit reprogramming the microcontroller during firmware development. Insome implementations, Circuit boards may be designed for ease oftestability such as using automated test fixture equipment.

Additionally the microcontroller may include on-chip EEPROM fornon-volatile storage of miscellaneous data for support of its functionalcapabilities, according to some embodiments. On-chip RAM may also bepresent in sufficient quantity for the microcontroller's functionalcapabilities. The microcontroller may also include an on-chip ADC 326with 8-bit resolution or greater. In this and/or other implementations,the ADC 326 contains four or more input channels.

In some embodiments, the sensor unit 12 includes a rain sensor 318employing hygroscopic material suitable for the detection ofprecipitation. This material typically has a useful lifetime around thatof the power source 324, about five years or more. Upon exposure toprecipitation, expansion of the hygroscopic material causes a change ina variable. This change in variable or a value derived from the changein the variable is provided to one channel of the microcontroller's ADC326.

The hygroscopic material and the mechanical structures designed tocontain it and translate its expansion to a linear displacement arecalibrated, in some embodiments. This calibration establishes theability of the structure to detect between about ⅛ and ¾ inches ofprecipitation with a repeatability of ±20% or better. Unit-to-unitvariations in the detection of identical amounts of precipitation are±20% or less.

In one embodiment, in order to detect ambient temperature, the sensorunit 12 may also employ a temperature-sensitive device 322 such as athermistor, temperature-dependent current source, and/or other suchdevice. For example, a “direct digital” temperature sensor may beemployed as the temperature sensor 322. According to some embodiments,the temperature-sensitive device 322 is capable of detecting an ambienttemperature of 37° F. with a tolerance of ±5% or better. In someembodiments, the output signal from the temperature-sensitive device isprovided to one channel of the microcontroller's ADC.

In one or more embodiments, the sensor unit 12 is also equipped with alight indicator, such as a bi-color LED capable of illumination in redor green. The LED is visible through a clear window in the unit'splastic enclosure to eliminate the need to create a penetration throughthe plastic. The enclosure of the sensor unit 12 may also include amounting bracket for outdoor mounting of the sensor unit.

In some embodiments, when the battery 324 is inserted into the sensorunit 12, the unit powers up and enters “INITIALIZATION” operationalmode. During the initialization mode the sensor may receive a signalfrom the interface unit 14 to establish a wireless and/or wiredcommunication path between the interface unit 14 and the sensor unit 12.Alternatively, the sensor unit may initiate a message to one or moreinterface units 14 and start the initialization process. Once the sensorunit 12 receives the set up signal from the interface unit it will sendback an acknowledge signal. In one or more embodiments, theacknowledgment signal comprises identification information and/or otherlocal information. The interface unit 14 then receives theacknowledgment message. In one embodiment, the interface unit 14extracts the ID information and/or other information from the signal andmay store the data onto memory 418. According to some implementations,the interface unit 14 may use the data from the setup acknowledge signalin the future to validate communication from the sensor unit to ensuethat it only responds to communication from the sensor units it ispaired up with. Similarly, in some embodiments the setup signal maycomprise ID information about the interface unit 14 which the sensorunit may retrieve and store in memory 314, for example for futurevalidation of signals from the interface unit. After processing theacknowledgment signal at the interface unit 14 the sensor unit 12 andthe interface unit 14 are paired up and may communicate through thewireless and/or wired path 15. In some embodiments, before sending anacknowledgment message the sensor unit 12 will determine if certaincriteria are met. For example in one embodiment, the sensor unit 12 maydetermine whether there is user input at the sensor unit and will onlytransmit the acknowledge message when user input is present at thesensor unit. For example, the sensor unit may check to see if theplunger on the rain sensor unit is fully depressed.

Additionally or alternatively, during this mode, the microcontroller 312may complete firmware initializations in order to set the unit up foroperation. In one embodiments, once firmware initializations arecompleted, the microcontroller 312 reads the battery voltage under fullload (with the exception of the radio transmitter 316). If the batteryvoltage is above a minimum voltage for proper operation in “NORMAL”mode, the sensor unit 12 transmits a signal, i.e. a BATTERY_OK message,to the interface unit 14. This signal may be transmitted at a definedpower and/or transmitted utilizing the maximum transmitter poweravailable. The interface unit 14 may respond to receipt of this messageby sending an acknowledgement signal, i.e., a BATTERY_OK_ACKNOWLEDGEmessage back to the sensor unit 12. Upon receipt of this message, thesensor unit 12 enters a sleep or “NORMAL” operational mode.

Alternatively, if the measured battery voltage is below the minimumallowable voltage for proper operation in “NORMAL” mode, the unittransmits a low battery warning, e.g., a LOW_BATTERY_WARNING message, tothe interface unit 14. This message is transmitted at a defined powerand/or utilizing the maximum transmitter power available. The interfaceunit 14 responds to receipt of this message by sending anacknowledgment, e.g., a LOW_BATTERY_ACKNOWLEDGE message, back to thesensor unit 12. Upon receipt of this message, the sensor unit 12 enters“LOW BATTERY” operational mode.

In some embodiments, during “INITIALIZATION” mode the bi-color LED willilluminate in both red and green for a period of one second. Thisprovides a visual indication to the user that the unit has powered upand is operating. In other embodiments the light indicator may blink anumber of times displaying the signal and/or connection strength betweenthe sensor unit 12 and the interface unit 14.

In some embodiments, while the sensor unit 12 is in “NORMAL” mode, themicrocontroller 312 brings itself out of its low-power mode periodicallyto query the sensors and/or other peripheral devices. In one or moreembodiments, the microcontroller 312 will process the data to determineif there has been any change in the data obtained from the sensorsand/or other devices, e.g., a change in temperature, change in theamount of rain, etc. When the controller determines that a change hasoccurred, it will initiate a transmission to the interface unit 14.Additionally or alternatively, in some embodiments, the sensor unit 12will initiate a transmission to the interface periodically, at fixedintervals, sending the data received from the sensors. In thisembodiment, the data may be queried from the sensors at the time of thetransmission or may be retrieved from memory 314. In an alternativeembodiment, while in “NORMAL” mode, the sensor unit 12 typically willnot initiate a radio transmission to the interface unit 14. The sensorunit 12 will minimize its power consumption to maximize its batterylife, and will place its radio receiver device into a “quasi-sleep”mode. In this embodiment, while in “quasi-sleep” mode, the radioreceiver is capable of detecting the presence of an incoming message butmay accomplish this without the need to apply full power to all receivercircuitry. In one or more embodiments, during normal mode the bi-colorLED may be extinguished.

At intervals, for example of approximately once per day, themicrocontroller 312 brings itself out of its normal or sleep mode andactivate one or more and typically all peripheral systems on the unit(with the exception of the radio transmitter 316). Once all peripheralshave been activated, the microcontroller 312 performs a measurement ofthe full-load battery voltage. The resulting measurement, at least insome embodiments, is stored in memory 314 and/or transmitted to theinterface unit 14. Additionally or alternatively, the resultingmeasurement may be compared with a non-volatile constant stored inmemory 314, i.e., EEPROM, to determine if the battery is nearing the endof its useful life. In order to accurately make this determination, themicrocontroller may also make a measurement of the ambient temperatureto calibrate the measured battery voltage. In some embodiments, if thefull-load battery voltage is below the minimum allowable voltage (end ofbattery life is approaching), the microcontroller may switch the systeminto “LOW BATTERY” mode.

While in “Normal” mode the sensor unit 12 may respond to a number ofmessages from the interface unit 14. For example, the sensor unit 12responds to a SENSOR_STATUS_REQUEST message from the interface unit 14.Upon receipt of a SENSOR_STATUS_REQUEST message, the microcontrollerinitiates a measurement of the hygroscopic material displacement,ambient temperature, and full-load battery voltage. After thesemeasurements have been completed, the sensor unit 12 constructs amessage packet containing the results of the measurements. It alsoincludes in the message packet the RSSI value observed during thereceipt of the SENSOR_STATUS_REQUEST message. The entire message packetis transmitted to the interface unit 14 in the form of a SENSOR_STATUSmessage.

The sensor unit 12 may also respond to a LINK_QUALITY_REQUEST messagefrom the interface unit 14. A LINK_QUALITY_REQUEST message instructs thesensor unit 12 to transmit a LINK_QUALITY message back to the interfaceunit 14 at the power level specified in the payload of theLINK_QUALITY_REQUEST. The LINK_QUALITY message contains data packetsthat indicate the requested power level for the transmission and theRSSI value observed during the receipt of the LINK_QUALITY_REQUESTmessage.

Additionally, the sensor unit 12 responds to a TX_POWER_ASSIGN messagefrom the interface unit 14. A TX_POWER_ASSIGN message instructs thesensor unit 12 to utilize a specific power level for futuretransmissions (with the exception of a LINK_QUALITY, where the transmitpower is assigned by a LINK_QUALITY_REQUEST). The sensor unit 12responds with a TX_POWER_ACKNOWLEDGE message that contains a packetindicating the assigned transmit power and the RSSI value observedduring the receipt of the TX_POWER_ASSIGN message.

The sensor unit 12 responds to a VERSION_REQUEST message from theinterface unit 14. A VERSION_REQUEST message instructs the sensor unit12 to transmit a VERSION message containing the unit's unique ID number,the version number of the firmware stored in its FLASH memory, and theRSSI value observed during the receipt of the VERSION_REQUEST message.

In some embodiments, in “LOW BATTERY” operational mode the sensor unit12 may notify the interface unit 14 that it has detected a low batterycondition. It may also attempt to reduce power consumption byeliminating or reducing the frequency of performing non-essentialfunctions. During the “LOW BATTERY” mode the bi-color LED will beextinguished at all times.

In one or more embodiments, when a low battery condition is detected,the sensor unit 12 initiates a LOW_BATTERY_WARNING message to theinterface unit 14. In some embodiments, the power level used for thistransmission is the power that was last assigned by the interface unit14, e.g., through a TX_POWER_ASSIGN message. In one implementation, theLOW_BATTERY_WARNING message instructs the interface unit 14 to transmitan acknowledgment, e.g., a LOW_BATTERY_ACKNOWLEDGE message, indicatingthat the LOW_BATTERY_WARNING was correctly received. In one embodiment,in the event that the sensor unit 12 does not receive aLOW_BATTERY_ACKNOWLEDGE message, it may increase the transmitter powerand resend the LOW_BATTERY_WARNING message. In some embodiments, thetransmitter power may be increased with each subsequent attempt tocontact the interface unit 14 until an acknowledgment, e.g., aLOW_BATTERY_ACKNOWLEDGE message, is received.

In one or more embodiments, once an acknowledgment has been received thesensor unit 12 may reduce the number of periodic updates it sends to theinterface units. Additionally, or alternatively, the sensor unit 12 mayalso reduce the number of times it wakes up to query the sensors, and/orother peripheral devices. Alternatively, once an acknowledge message hasbeen received the sensor unit 12 may not initiate further transmissions,but only acknowledges messages received from the interface unit 14.

FIG. 26 illustrates one possible implementation of the “TEST”operational mode utilized during the installation of the sensor unit 12.This process provides the installer with a quick andsimple-to-understand process for determining that the sensor unit 12 isinstalled at a location with adequate radio reception from the interfaceunit 14. In some embodiments, the “TEST” operational mode is initiatedby the interface unit 14 in response to a “Press and Hold” actuation ofthe button 820 on the interface unit 14. Still further, in someimplementations the “TEST” operational mode terminates automaticallyafter a set period of time, e.g., 15 minutes.

Further, according to some implementations, the “TEST” operational modeconsists of an exchange of radio messages between the sensor unit 12 andthe interface unit 14 to determine whether or not the sensor unit 12 ispositioned at a satisfactory location. Moreover, in someimplementations, the test operational mode allows the installer todetermine the best possible location for the sensor unit 12 relative tothe interface unit 14 before the sensor unit 12 is fixed at a location.In one or more embodiments, a location may be deemed satisfactory if thefollowing conditions are satisfied:

RSSI_(SENSOR)≧RSSI_(SENSORMIN)

RSSI_(INTERFACE)≧RSSI_(INTERFACEMIN)

P_(TXSENSOR)≦P_(TXNOMINAL)

Where RSSI_(SENSOR) is the RSSI value of the RF signal transmitted fromthe interface unit 14 as received at the sensor unit 12.RSSI_(SENSORMIN) is the minimum allowable value of RSSI_(SENSOR) toachieve communication reliability for the system. RSSI_(INTERFACE) isthe RSSI value of the RF signal transmitted from the sensor unit 12 asreceived at the interface unit 14. RSSI_(INTERFACEMIN) is the minimumallowable value of RSSI_(INTERFACE) to achieve communication reliabilityfor the system. P_(TXSENSOR) is the transmitter power employed by thesensor unit 12. P_(TXNOMINAL) is the maximum transmitter power allowedfor the sensor unit 12 to utilize for operations under normal operatingconditions. In some embodiments, the power level may typically be atleast 6.0 dB below the maximum output power achievable by thetransmitter, and may be selected to achieve the overall battery lifetimeof the sensor unit 12 is adequate.

According to some implementations, While in the “TEST” operational mode,the “TEST” operational mode flag in the FLAGS field of all messagepayloads may be SET.

Still referring to FIG. 26, in step 2610 the message transactions areinitiated by the interface unit 14 at two-second intervals, andculminate in the determination of the optimal location to install thesensor unit and/or to determine the minimum transmitter power for thesensor unit 12 to communicate with the interface unit 14 to achieve thedesired system reliability. In step 2612 the interface unit sends a testmessage to the sensor unit. Next, in step 2614 the sensor unit receivesthe signal and determines and responds with an acknowledgment message.In one or more implementations, the sensor unit then moves to step 2616where it determines the signal strength of the test message and displaysthe signal strength (e.g., as a number of blinks of the light emittingdiode). In some embodiments, as the location of the sensor unit 12 ischanged by the installer and the sensor unit 12 automatically determinesand displays the test acknowledge signal strength. According to someimplementations, the signal strength is automatically updated by thesensor unit 12 with each two-second “TEST” operational mode messageexchange. In one embodiment, the sensor unit 12 displays the signalstrength through an indicator, e.g., an LED, where, for example, theindicator blinks a number of times representing the signal strength at aparticular location. Alternatively, or additionally the indicator may bean LCD display that displays the signal strength. The installer may thenchange the location of the sensor unit 12 and by observing the signalstrength in different areas may determine a location to install thesensor unit 12. Alternatively, in some embodiments, when the location ofthe sensor unit is determined to be adequate based on the decisioncriteria, a bi-color LED may be illuminated green. If the location isdetermined to be inadequate, the bi-color LED may be illuminated red. Inone embodiment, the status of the bi-color LED is updated with eachtwo-second “TEST” operational mode message exchange. In someembodiments, this initialization process continues for a preset period,e.g., 15 minutes where the interface unit and the sensor unit exchangemessages to allow the user to find the optimal location for the sensorunit in terms of signal strength.

In some embodiments, the TEST message may be identical in form to theLINK_QUALITY_REQUEST message with the exception that the “TEST”operational mode flag in the FLAGS field of the message payload may beSET. According to some implementations, the sensor unit 12 responds witha TEST_ACKNOWLEDGE message. This message may be identical in form to theLINK_QUALITY_ACKNOWLEDGE message with the exception that the “TEST”operational mode flag in the FLAGS field of the message payload is SET.

In one implementation, in step 2620 the interface unit 14 decodes themessage to obtain the value of RSSI_(INTERFACE). In step 2622 theinterface unit determines if RSSI_(SENSOR)≧RSSI_(SENSORMIN). If thecondition is satisfied, in step 2624 the interface unit checks to seewhether the last message sent was a TX_POWER_INCREASE message. If thelast message received was not a TX_POWER_INCREASE message, in step 2626the interface unit 14 issues a TX_POWER_DECREASE message to the sensorunit 12. In step 2632 the sensor unit determines whether it is at theminimum TX power necessary for proper functioning, in step 2634 thesensor unit send a TX_LEAST_POWER message to the interface unit. Inresponse to this message, in step 2636, the interface unit issues aTX_LEAST_POWER_ACKNOWLEDGEMENT message to the sensor unit 12.Alternatively, when in step 2632 the sensor unit is not at the minimumTX power, then in step 2638 the sensor unit 12 decreases its transmittalpower by the smallest possible amount and replies with aTX_POWER_DECREASE_ACKNOWLEDGE message.

Returning to step 2624, if the last message sent by the interface unitwas a TX_POWER_INCREASE message, in step 2644 the interface unit thenissues a TX_MINIMUM_POWER message to the sensor unit 12 notifying it ofthe transmitter power for use in future transmissions. In step 2646sensor unit decodes the message and obtains the RSSI_(SENSOR) value. Instep 2648 the sensor responds with a TX_MINIMUM_POWER_ACKNOWLEDGEmessage.

If alternatively in step 2622 RSSI_(INTERFACE)<RSSI_(INTERFACEMIN) hasbeen satisfied, in step 2628, the interface unit 14 issues aTX_POWER_INCREASE message to the sensor unit 12 notifying it to increaseits transmitter power by the smallest possible amount. In response tothe TX_POWER_INCREASE message, in step 2652 the sensor unit determinesif it is at the maximum TX power it is capable of producing. If thesensor unit is not at the maximum TX power, then in step 2658 the sensorunit 12 increases the transmitter power by the smallest allowableincrement and initiates a TX_POWER_INCREASE_ACKNOWLEDGE message to theinterface unit 14. Alternatively, if the sensor unit 12 is already setto transmit the maximum power it is capable of producing, the processcontinues to step 2654 where the sensor unit initiates a TX_MOST_POWERmessage to the interface unit 14 indicating that it may no longerincrease its transmit power. In response to this message, in step 2656the interface unit issues a TX_MOST_POWER_ACKNOWLEDGE message to thesensor unit 12.

In one embodiment, after the initializations are complete the sensorunit 12 may query all of the sensors and/or other peripheral devices andconstruct a data packet comprising atmospheric data, battery strength,signal strength, and/or other data and forward the data packet to theinterface unit 14.

An alternative implementation of “TEST” operational mode is illustratedin FIG. 22. The “TEST” operational mode is utilized during theinstallation of the sensor unit 12 to provide the installer with a quickand simple-to-understand process for determining that the sensor unit 12is installed at a location with adequate radio reception from theinterface unit 14. Further, the “TEST” operational mode is initiated bythe interface unit 14 in response to a “Press and Hold” actuation of thebutton 820 on the interface unit 14. Still further, the “TEST”operational mode terminates automatically after a period of fiveminutes.

Additionally, the “TEST” operational mode consists of an exchange ofradio messages between the sensor unit 12 and the interface unit 14 todetermine whether or not the sensor unit 12 is positioned at asatisfactory location. A location is deemed to be satisfactory if thefollowing conditions are satisfied:

RSSI_(SENSOR)≧RSSI_(SENSORMIN)

RSSI_(INTERFACE)≧RSSI_(INTERFACEMIN)

P_(TXSENSOR)≦P_(TXNOMINAL)

Where RSSI_(SENSOR) is the RSSI value of the RF signal transmitted fromthe interface unit 14 as received at the sensor unit 12.RSSI_(SENSORMIN) is the minimum allowable value of RSSI_(SENSOR) toachieve communication reliability for the system. RSSI_(INTERFACE) isthe RSSI value of the RF signal transmitted from the sensor unit 12 asreceived at the interface unit 14. RSSI_(INTERFACEMIN) is the minimumallowable value of RSSI_(INTERFACE) to achieve communication reliabilityfor the system. P_(TXSENSOR) is the transmitter power employed by thesensor unit 12. P_(TXNOMINAL) is the maximum transmitter power allowedfor the sensor unit 12 to utilize for operations under normal operatingconditions. This power level is typically at least 6.0 dB below themaximum output power achievable by the transmitter, and is selected toachieve the overall battery lifetime of the sensor unit 12 is adequate.

While in the “TEST” operational mode, the “TEST” operational mode flagin the FLAGS field of all message payloads will be SET.

Still referring to FIG. 22, in step 2210 the message transactions areinitiated by the interface unit 14 at two-second intervals, andculminate in the determination of the minimum transmitter power for thesensor unit 12 to communicate with the interface unit 14 to achieve thedesired system reliability. If the location of the sensor unit 12 isdetermined to be adequate based on the decision criteria, the bi-colorLED is illuminated green. If the location is determined to beinadequate, the bi-color LED is illuminated red. The status of thebi-color LED is updated with each two-second “TEST” operational modemessage exchange.

In step 2212 the interface unit sends a TEST message to the sensor unit12. In step 2214 the sensor unit 12 responds to the TEST message fromthe interface unit 14. The TEST message may be identical in form to theLINK_QUALITY_REQUEST message with the exception that the “TEST”operational mode flag in the FLAGS field of the message payload is SET.The sensor unit 12 responds with a TEST_ACKNOWLEDGE message. Thismessage may be identical in form to the LINK_QUALITY_ACKNOWLEDGE messagewith the exception that the “TEST” operational mode flag in the FLAGSfield of the message payload is SET.

In step 2216 the interface unit 14 decodes the message to obtain thevalue of RSSI_(INTERFACE). In step 2218 the interface unit determines ifRSSI_(SENSOR)≧RSSI_(SENSORMIN). If the condition is satisfied, in step2220 the interface unit checks to see whether the last message sent wasa TX_POWER_INCREASE message. If the last message received was not aTX_POWER_INCREASE message, in step 2222 the interface unit 14 issues aTX_POWER_DECREASE message to the sensor unit 12. In step 2224 the sensorunit determines whether it is at the minimum TX power necessary forproper functioning, in step 2228 the sensor unit send a TX_LEAST_POWERmessage to the interface unit. In response to this message, in step2230, the interface unit issues a TX_LEAST_POWER_ACKNOWLEDGEMENT messageto the sensor unit 12. Following receipt of the message the sensor unitcontinues to step 2250. Alternatively, when in step 2224 the sensor unitis not at the minimum TX power, then in step 2226 the sensor unit 12decreases its transmittal power by the smallest possible amount andreplies with a TX_POWER_DECREASE_ACKNOWLEDGE message.

Returning to step 2220, if the last message sent by the interface unitwas a TX_POWER_INCREASE message, in step 2244 the interface unit thenissues a TX_MINIMUM_POWER message to the sensor unit 12 notifying it ofthe transmitter power for use in future transmissions. In step 2246sensor unit decodes the message and obtains the RSSI_(SENSOR) value. Instep 2248 the sensor responds with a TX_MINIMUM_POWER_ACKNOWLEDGEmessage. Following step 2248, in step 2250 the sensor unit determines ifRSSI_(SENSOR)≧RSSI_(SENSORMIN). When the condition is satisfied, then instep 2256 the sensor unit determines whether P_(TXSENSOR)≦P_(TXNOMINAL).If this condition is satisfied, then the sensor unit continues to step2258 where the bi-color led is illuminated green, indicating that thesensor location is acceptable. Alternatively, if in step 2256 the sensorunit determines the P_(TXSENSOR)>P_(TXNOMINAL) then in step 2252 thebi-color led is illuminated in red indicating that the sensor locationis unacceptable.

Similarly, if in step 2250 the sensor unit determines thatRSSI_(SENSOR)<RSSI_(SENSORMIN) process continues to step 2252, where thebi-color led is illuminated in red indicating that the sensor locationis unacceptable.

Following receipt of the message, in step 2216 the interface unit 14decodes the message and obtains the value of RSSI_(INTERFACE). Theinterface unit then repeats steps 2218-2226, as described above, untilRSSI_(INTERFACE)<RSSI_(INTERFACEMIN) has been satisfied by the powerdecrease. If this condition has been satisfied, in step 2232, theinterface unit 14 issues a TX_POWER_INCREASE message to the sensor unit12 notifying it to increase its transmitter power by the smallestpossible amount. In response to the TX_POWER_INCREASE message, in step2234 the sensor unit determines if it is at the maximum TX power it iscapable of producing. If the sensor unit is not at the maximum TX power,then in step 2236 the sensor unit 12 increases the transmitter power bythe smallest allowable increment and initiates aTX_POWER_INCREASE_ACKNOWLEDGE message to the interface unit 14.Alternatively, if the sensor unit 12 is already set to transmit themaximum power it is capable of producing, the process continues to step2238 where the sensor unit initiates a TX_MOST_POWER message to theinterface unit 14 indicating that it may no longer increase its transmitpower. In response to this message, in step 2240 the interface unitissues a TX_MOST_POWER_ACKNOWLEDGE message to the sensor unit 12. Thenin step 2252 the sensor unit causes the bi-color led to be illuminatedin red indicating that the sensor location is unacceptable.

In one or more implementations the interface unit 14 draws power fromthe main irrigation controller 30. The interface unit 14 may operatefrom 22 to 30.8 VAC input voltage. Typically, the interface unit 14operates by taking 24 VAC electrical power from its associatedirrigation controller. Additionally or alternatively, the interface unitmay comprise a power source, such a battery, solar power, and/or othersuch source, where the interface unit draws some or all of its powerfrom the power source.

In some embodiments, he interface unit 14 may be implemented utilizing alow-cost 8-bit microcontroller 414 that has sufficient computationalpower and speed to support all of the functional capabilities of theunit. In one embodiment, the microcontroller 414 may employ a quartzcrystal for generation of an internal clock signal. It may be desiredthat the same type of microcontroller be used in both the sensor unit 12and the interface unit 14.

According to some implementations, the microcontroller typically employsFLASH memory for storage of executable firmware, and is capable of beingprogrammed “in-system”. For example, an in-system programming port maybe available on the printed circuit board for accomplishing theprogramming process during final assembly. The in-system programmingport may be accessible via surface pads (through the use of “pogo” pinson an ICT fixture), in one or more embodiments. A programming header mayalso be available on the printed circuit board to permit reprogrammingthe microcontroller during firmware development. In some embodiments,the circuit board may be designed for ease of testability such as usingautomated test fixture equipment. In this embodiment, standard solderconnections with conformal coating are used for the circuit board.

In some implementations, the microcontroller 414 may also includeon-chip EEPROM for non-volatile storage of miscellaneous data requiredfor support of all functional capabilities. On-chip RAM is alsotypically present in sufficient quantity for all functionalcapabilities, according to some embodiments.

In some embodiments, the interface unit employs a single-chiptransceiver 412 which provides an analog or digital Received SignalStrength Indicator (RSSI) output signal. In one embodiment, where theRSSI output is an analog signal, it may be provided to one channel ofthe microcontroller's ADC.

The interface unit 14, according to some implementations, may also beequipped with a backlit LCD 816. The display may be capable ofdisplaying alphanumeric characters with 11-segment LCD digits. Asufficient number of LCD digits are provided to display at least thefollowing messages:

a) BATT OK

b) BATT LOW

c) BYPASS

d) NORMAL

e) INHIBIT

f) FREEZE

g) TEST

h) NO SIGNAL

i) NO SENSOR

j) NOISE

Additionally, or alternatively the interface unit may be capable ofdisplaying the mode and or status of the system through other means. Forexample, in one embodiment the user display 426 comprises a graphicdisplay capable of displaying the mode of operation or status of thesystem. For example, in one embodiment, the display 426 may display thestatus of the system using graphical symbols displayed on the graphicdisplay of the interface unit 14.

In some implementations, the interface unit 14 employs a “normallyclosed” relay device to permit breaking the COMMON return lineconnection between the sprinkler valve solenoids and the irrigationcontroller 30. In one or more embodiments, this relay may be actuated bya voltage that is compatible with the voltage output of one of themicrocontroller output pins. according to some implementations, themaximum current rating of the relay contacts may be no less than 3.0amperes.

In some embodiments, the interface unit 14 also employs a currentsensing device 420 to allow detection of the current flow in the COMMONreturn line. In one embodiment, when an irrigation cycle is commanded bythe irrigation Controller, current flows in the COMMON line. The currentsensor may detect this signal, triggering the microcontroller 414 toinitiate a SENSOR_STATUS_REQUEST to the sensor unit 12. In oneembodiment, when the SENSOR_STATUS message returned by the sensor unit12 indicates that irrigation should be inhibited, the currentinterruption relay 416 is OPEN, interrupting irrigation.

Additionally or alternatively, the interface unit 14 may employ avoltage sensing device 422, in one or more embodiments, to allowdetection of the voltage across the current interruption relay 416 inthe COMMON return line. When irrigation is being commanded by theirrigation controller 30 while the system 10 is commanding thatirrigation be inhibited, the voltage sensor 422 may monitor the voltageacross the relay contacts to determine when the irrigation cycle hasterminated. Once the irrigation cycle has terminated the interface unit14 will CLOSE the current interruption relay.

In some embodiments, the interface unit comprises a user input 424,wherein in one or more embodiments the user input allows the user tochange the mode of operation of the interface unit and/or perform otheradjustments in the operation of the interface unit 14. For example, inone embodiment, the interface unit 14 is equipped with a three-positiontoggle switch 814 to allow the user to configure the unit for thedesired operation. The switch has a CENTER position in addition to aLEFT and a RIGHT position. Placing the switch into the CENTER positionplaces the interface unit 14 into NORMAL operational mode whereirrigation is inhibited if sufficient precipitation has been detected bythe sensor unit 12. Placing the switch into the LEFT position places theinterface unit 14 into BYPASS mode, where irrigation will not beinhibited by the system. The RIGHT switch position is a spring-loaded“return to center”, automatically releasing back to CENTER when theswitch is no longer held in position. This spring-loaded position placesthe interface unit 14 unit into TEST operational mode. The interfaceunit may also include a way too override or shut-off the device.Alternatively, and or additionally, in one embodiment, the interfaceunit 14 is equipped with a touch screen comprising buttons that allowthe user to switch the mode of operation.

In some embodiments, the interface unit 14 unit is equipped with apushbutton switch 820 to allow the user to activate an LCD backlight fora period of five seconds. When the pushbutton is depressed, the LCDbacklight is illuminated. The LCD backlight remains illuminated for aperiod of time, e.g., 5 seconds, after the pushbutton has been released.In one or more embodiments, when the toggle switch on the interface unit14 is set to the BYPASS position, the LCD display continuously displaysthe “BYPASS” message.

In many embodiments, the interface unit 14 incorporates a user-friendlymethod of adjusting the rainfall level desired by the user. For example,the interface unit 14 may be equipped with a linearly-adjustable slideswitch 812 that allows the user to select the level of precipitation atwhich irrigation will be interrupted. In one or more embodiments,precipitation amounts between ⅛″ and ¾″ are selectable in a continuousmanner.

When power is first applied to the interface unit 14, the unit powers upand enters “INITIALIZATION” operational mode. In some embodiments,during the initialization mode, the microcontroller 414 executes theinitializations that need to be completed in order to set the unit upfor operation. During the initialization mode the interface unit mayalso attempt to pair up with one or more sensor units 12, such asillustrated in the system diagram of FIG. 34. In one implementation, theinterface unit will send a setup signal to one or more sensor units 12.Next, the interface unit may receive an acknowledgement signal from oneor more sensor units 12 in response to the setup signal. In someembodiments, the acknowledgment signal may comprise identificationand/or other information about the sensor unit. In some embodiments, theinterface unit 14 may store the data in memory 418 and/or use the datato pair up with the sensor unit 12. Once the setup is complete theinterface unit and sensor unit 12 may communicate through thecommunication path 15. In one embodiment, during “INITIALIZATION MODE”the LCD backlight may be continuously illuminated.

In one embodiment, after the initializations are complete the sensorunit 12 may query all of the sensors and/or other peripheral devices andconstruct a data packet comprising atmospheric data, battery strength,signal strength, and/or other data and forward the data packet to theinterface unit 14. The interface unit 14, according to someimplementations, may receive the data from the sensor unit 12, andprocess the data and display information about the sensor unit on theuser display 426.

Additionally or alternatively, in some embodiments, at the conclusion ofthe internal initializations, the microcontroller may retrieve from itsmemory 418, and more specifically the EEPROM, the identification numberof the sensor unit 12 with which it is associated and transmit aSENSOR_STATUS_REQUEST message. Upon receipt of a SENSOR_STATUS messagefrom the sensor unit 12, the interface unit 14 may process the message.In one embodiment, the interface unit 14 may further display theappropriate sensor unit 12 status message on the LCD display 426.

In one or embodiments, when no sensor unit is associated with theinterface unit 14, the user display 426 may display a “NO SENSOR”message and/or a similar message and or graphic display. In oneembodiment, when the “NO SENSOR” message is displayed the LCD backlightflashes on and off at a 4-second rate (two seconds on, two second off).According to one implementation, at the conclusion of the“INITIALIZATION” mode, the interface unit 14 enters “NORMAL” mode.

In some embodiments, the interface unit 14 spends the majority of itstime in the “NORMAL” operation mode. In “NORMAL” mode, the LCD backlightis OFF unless illuminated by the user by depressing the pushbutton, orby an event requiring its illumination.

In one or more embodiments, when the interface unit 14 is set to BYPASS,the current interruption relay is set to CLOSED. In one implementation,a “BYPASS” message may be continuously displayed on the LCD. In this orother implementations, The LCD backlight may be OFF.

In some embodiments, during “NORMAL” mode, the interface unit 14 willcontinually monitor the open-circuit voltage across the currentinterruption relay to detect when irrigation is being commanded from theirrigation controller 30. In this embodiment, when 24 VAC is detectedacross the current interruption relay, the interface unit 14 initiates aSENSOR_STATUS_REQUEST to its associated sensor unit 12. If theSENSOR_STATUS reply message received from the sensor unit 12 indicatesthat irrigation should be inhibited, the current interruption relay isOPENED. Once the relay has been OPENED, the interface unit 14 maymonitor the current flow in the COMMON return line to detect whenirrigation has ceased, at which time the current interruption relay isset to CLOSE. Alternatively, if the SENSOR_STATUS reply message receivedfrom the sensor unit 12 indicates that irrigation should be permitted,the current interruption relay remains in its default CLOSED state. Insome embodiments, while in normal mode, the current interruption relayis normally CLOSED, unless the SENSOR_STATUS reply message received fromthe sensor unit 12 indicates that irrigation should be inhibited. Inthese embodiments if system failure occurs at any time the relay is inits default CLOSED state.

Alternatively, in some embodiments, the interface unit will open andclose the relay based on transmission of signals initiated from thesensor unit. In one embodiment the sensor unit 12 will initiate anupdate message to the interface unit when it senses a change in one ormore of the data retrieved from sensors and/or other peripheral devices.Additionally or alternatively, the sensor unit may initiatecommunication with the interface unit 14, in some embodiments, at fixedintervals, e.g., 4 times a day, when it may query one or more sensorsand/or other devices and send an update signal to the interface unit 14.In one or more embodiments the frequency of transmission of periodicupdates based on internal and/or external criteria. For example, in oneembodiment the sensor unit 12 may decrease the number of updates it willsend the interface unit 12 during the Low Battery mode. Additionally oralternatively, the sensor unit may also reduce the number of updates ittransmits to the interface unit 14 during low temperature or hibernationmode. In some embodiments, in addition to these messages the sensor unitmay also send a message to the interface unit when it receives a requestfor data from the interface unit 14.

In one embodiment, after the SENSOR_STATUS message, or an update messageis received from the sensor unit 12, the interface unit 14 maycontinuously displays the appropriate system status message on the userdisplay 426. In one embodiment, for example:

a) when irrigation is currently enabled, the message “NORMAL” isdisplayed

b) when irrigation is currently disabled because of precipitation, themessage “INHIBIT” is displayed

c) when irrigation is currently disabled because of low temperature, themessage “FREEZE” is displayed

In one implementation, while these messages are being displayed, the LCDbacklight may be turned OFF.

Alternatively, in another exemplary embodiment, the display may be agraphical display. In this and other embodiments, the interface unit maydisplay the status and other data received from the sensor unit througha graphical representation.

In many embodiments, while in “NORMAL” operational mode the interfaceunit 14 responds to a BATTERY_OK message from the sensor unit 12. Uponreceipt of this message the interface unit 14 may send aBATTERY_OK_ACKNOWLEDGE message back to the sensor unit 12. In oneembodiment, after transmitting this message, the message “BATT OK” isdisplayed on the display for a certain period, e.g., five seconds. In analternative embodiment, the interface unit may display the batterystrength of the sensor unit 12 on the display 426.

The interface unit 14, in some embodiments, may also responds to a lowbattery warning message, e.g., a LOW_BATTERY_WARNING message, from thesensor unit 12. In one embodiment, the interface unit 14 may respond toreceipt of this message by sending a LOW_BATTERY_ACKNOWLEDGE messageback to the sensor unit 12. In one implementation, after this message istransmitted a low battery indication, e.g., a “BATT LOW” message, isdisplayed continuously on the user display 426. Additionally, in someembodiments, the LCD backlight is flashed on and off at a 4-second rate(two seconds on, two second off). In some embodiments, the otherirrigation control functions at the interface unit 14 continue tooperate normally. In one embodiment, in order to indicate this, the lowbattery indication is displayed alternately with the status indicationthat is appropriate for the current state of the system (e.g., “NORMAL”,“INHIBIT”, “FREEZE”, “BYPASS”, etc.).

In some embodiments, at fixed intervals, e.g., approximately once perday, the interface unit 14 initiates a measurement of the communicationslink quality, for example by issuing a LINK_QUALITY_REQUEST message tothe sensor unit 12. Upon receipt of the response from the sensor unit12, for example the LINK_QUALITY_ACKNOWLEDGE message, the interface unit14 determines if the value of RSSI_(INTERFACE) satisfies the condition:

RSSI_(INTERFACE)≧RSSI_(INTERFACEMIN).

In one embodiment, when RSSI_(INTERFACE)<RSSI_(INTERFACEMIN) theinterface unit 14 may send a power increase message, for example aTX_POWER_INCREASE message, to the sensor unit 12. In one embodiment thesensor unit 12 may respond to the message by increasing its transmitpower by the smallest possible amount and reply, for example with aTX_POWER_INCREASE_ACKNOWLEDGE message. Upon receipt of this message, inone or more implementations, the interface unit 14 may determine if thecondition RSSI_(INTERFACE)≧RSSI_(INTERFACEMIN) has been satisfied by thepower increase. If this condition has been satisfied, the interface unit14 may issues a message, e.g., a TX_MINIMUM_POWER message, to the sensorunit 12 notifying it of the transmitter power to use for futuretransmissions. Alternatively, when this condition is not satisfied, theinterface unit 14 may continue to issue power increase requests, e.g.,TX_POWER_INCREASE messages, to the sensor unit 12 until the condition issatisfied and/or a preset period of time has lapsed. In someembodiments, when the sensor unit 12 reaches the maximum power that itmay transmit during this process, it may send a message indicating thatit has reached it maximum power level, e.g., a TX_MOST_POWER message, tothe interface unit 14. In this case, the interface unit 14 may respondwith an acknowledgment message, e.g., a TX_MOST_POWER_ACKNOWLEDGEmessage, and terminate the power adjustment process.

Alternatively, according to some embodiments, whenRSSI_(INTERFACE)≧RSSI_(INTERFACEMIN), the interface unit may 14 issues amessage to the sensor unit 12, requesting that the sensor unit 12decrease its transmit power, e.g., a TX_POWER_DECREASE message. In oneimplementation, as a result of this message the sensor unit 12 maydecrease its transmit power by the smallest possible amount and mayfurther reply with an acknowledgment message, for example aTX_POWER_DECREASE_ACKNOWLEDGE message. Upon receipt of this message, theinterface unit 14 may determine if the conditionRSSI_(INTERFACE)<RSSI_(INTERFACEMIN) has been satisfied by the powerdecrease, according to some implementations. In one embodiments, whenthis condition has been satisfied, the interface unit 14 may issue arequest to the sensor unit 12 notifying it to increase its transmitterpower by the smallest possible amount, e.g., TX_POWER_INCREASE message.The sensor unit 12 may respond to the request with an acknowledgementmessage, e.g., a TX_POWER_INCREASE_ACKNOWLEDGE message, and, in one ormore embodiments, the interface unit 14 may verify that the conditionRSSI_(INTERFACE)≧RSSI_(INTERFACEMIN) is now satisfied. The interfaceunit 14 may then issue a message to the sensor unit 12 notifying it ofthe transmitter power to use for future transmissions, e.g., aTX_MINIMUM_POWER message.

In some embodiments, so long as the conditionRSSI_(INTERFACE)<RSSI_(INTERFACEMIN) is not satisfied, the interfaceunit 14 may continue to issue requests to the sensor unit 12 notifyingit to decrease its transmitter power, e.g., a TX_POWER_DECREASEmessages, until the condition is satisfied. In one embodiment, once thesensor unit 12 reaches the minimum power that it may transmit duringthis process, it will send a message to the interface unit notifying itthat it has reached its minimum power, e.g., a TX_LEAST_POWER message.In this or other embodiments, the interface unit 14 may respond with anacknowledgment, for example a TX_LEAST_POWER_ACKNOWLEDGE message, andmay further terminate the power adjustment process.

As described with respect to FIGS. 22 and 26, the “TEST” mode may beused during the installation of the sensor unit 12 and provides a methodfor a single installer to easily determine whether or not the proposedlocation for the sensor unit 12 will result in satisfactory signalreception and communications reliability in one or more embodiments. Inone implementations, the “TEST” mode is initiated by switching thetoggle switch to “TEST” mode and holding it for a minimum of threeseconds. In this embodiment, after this time requirement has been met,the interface unit 14 continuously displays an indication, e.g., themessage “TEST”, on the user display 426. In one embodiments, the LCDbacklight may be continuously illuminated while in “TEST” mode.Additionally or alternatively, the test mode may be initiated throughother forms of user input, e.g., activating a test button, selecting thetest option, etc. In one embodiment, the test mode may also be initiatedby the interface unit once the interface unit is powered up and pairedwith one or more sensor units.

After the test mode has been initiated, according to someimplementations, the interface unit 14 may initiate a TEST message atintervals of no more frequently than, for example, two seconds.Alternative procedures followed throughout the “TEST” mode are describedin the flowchart depicted in FIGS. 22 and 26. In some embodiments, the“TEST” mode may be terminated by the operator, for example by selectingand holding the toggle switch in the “TEST” position for a period, suchas, a period of no less than two seconds, and/or automatically after aperiod of, for example, fifteen minutes.

In many embodiments, message traffic between the interface unit 14 andsensor unit 12 typically occur in pairs, i.e, for every message that issent, there is an acknowledgement.

In one embodiment, in the event that the sender of an initial messagedoes not receive an acknowledgement corresponding to the message sentwithin a period of time (e.g., five seconds), the originator of themessage may assume that the message was lost. In one embodiment,retransmission of the message may be attempted for a period (e.g., oneminute). When the message may not be successfully transmitted andacknowledged within a period (e.g., one minute), in one or moreembodiments, the sender of the message may assume either that thecommunications channel is suffering from an unusually high level ofinterference or that a malfunction has occurred at the other end of thecommunications link.

In order to assess potential interference in the communications channel,both the interface unit 14 and the sensor unit 12 may periodicallymonitor the RSSI values obtained from the receiver chip during periodswhere no message traffic is being passed, according to some embodiments.In one embodiment, these values may be noted and stored, e.g. in ahistogram, so that a statistical archive of the distribution of noiselevels at the sensor unit 12 and interface unit 14 locations isavailable with which to assess the communications channel at any giventime. In some implementations, when no message traffic is being passed,the interface unit 14 may sample the RSSI value from its receiver chipat intervals of one minute. In one or more embodiments, the sensor unit12 may sample the RSSI value from its receiver chip at fixed intervals,e.g. one hour.

In some embodiments, after a failure to receive a timely acknowledgementto a message that has been sent, the originator of the message maysample the RSSI value from its receiver chip and may further assesswhether or not the sample obtained meets some criteria, for examplewhether the sample obtained lies within the bins of the histogramassociated with the expected noise floor. In one implementation, when itis determined that an unusually high noise level is present, an attemptat a retransmission may be made at the maximum possible transmitterpower. when this attempt fails to result in a successfulacknowledgement, in some embodiments, the device may sample the RSSIvalue from its receiver chip at fixed intervals, e.g. 15 minuteintervals, and may retransmit the message when the noise level hasreturned to its nominal value.

In one embodiments when a certain amount of time lapses withoutreduction in noise level the interface and/or sensor unit may ceaseattempts to transmit the message. For example, in one exemplaryembodiment, when 24 hours elapses with no reduction in the atmosphericnoise level, the interface unit 14 may ceases attempting to retransmitthe message. In one implementation of this exemplary embodiment, theinterface unit may continuously display an indication of the presence ofnoise, e.g. the “NOISE” message, on the user display 426. In thisembodiment, while this indication is being displayed, the LCD backlightmay be illuminated continuously. In one embodiment, when the noise levelhas returned to its nominal level, the interface unit 14 may initiate amessage, e.g. a LINK_QUALITY_REQUEST message, to re-establish thecommunications link and configure the appropriate transmitter power forthe sensor unit 12. In one exemplary embodiment, if 1 hour elapses withno reduction in the atmospheric noise level, the sensor unit 12, theunit may cease attempting to retransmit the message.

Alternatively, when sampling the RSSI value from the receiver chip, whenthe device determines that no excess atmospheric noise is present in thecommunications channel; it may presume that the device at the other endof the wireless link has failed.

In one embodiment when the interface unit 14 determines that the sensorunit 12 has failed, it may continue to attempt making contact with thesensor unit 12 at fixed intervals, e.g. five-minute intervals, for aperiod, e.g., 24 hours. In one embodiment, when no contact with thesensor unit 12 is made after a certain period of time, e.g. 24 hours,the interface unit 14 may cease further attempts at contacting thesensor unit 12 and, in one or more embodiment, may continuously displayan indication that communication has failed, e.g. the “NO SIGNAL”message, on the user display. In one embodiment, while this message isdisplayed, the LCD backlight is ON. In some embodiments, the interfaceunit may reattempt to communicate with the interface unit after a periodof time has lapsed.

Further, in some embodiment, when the sensor unit 12 determines that theinterface unit 14 has failed, it may continue to attempt making contactwith the interface unit 14 at fixed intervals, e.g. five-minuteintervals, for a certain period of time, e.g. one hour. In someembodiments, when communication has not been re-established after thisperiod, the sensor unit 12 may cease further attempts at contacting theinterface unit 14. In one embodiment, no further transmissions may beattempted until the interface unit 14 attempts to establish contact withthe sensor unit 12. Alternatively, in some embodiments, the sensor unit12 may try to reconnect to reestablish communication with the interfaceunit 14 after a certain period of time.

In some implementations of the rain sensor system 10, communicationmessages may comply with a desired Protocol. As such messages may havethe following format:

Start End Frame Message Check- Frame Preamble Marker Length Data sumMarker F5hex F5hex 1Chex 1 byte up to 1 byte 1Dhex 255 bytes

The preamble consists of 2 or more F5 (hex) transmissions. The purposeof the preamble is to give the receiving device an opportunity to syncup with the transmitting device.

Packet frames use the byte 1C hex as the start of frame marker and 1Dhex as the end of frame marker. When the payload contains a data byteequal to 1C or 1D, that byte is replaced by the sequence 1B, 01 or 1B,03. When the payload contains a data byte equal to 1B, that byte isreplaced by the sequence 1B, 02. Upon reception, sequences 1B, 01 arereplaced as 1C, sequences 1B, 02 are replaced as 1B, and sequences 1B,03 are replaced as 1D. This is similar to SLIP protocol used for TCP/IP.Packets start with the value 1C, and that value typically does notappear in the payload. Packets end with the value 1D, and that valuetypically does not appear in the payload. It may be desirable in someinstances that the length, message data or checksum contain thecombination of 1B followed by one of a 01, 02 or a 03.

The length element is a single byte that describes the length of themessage data element in terms of byte count. For example, a frame thathas 4 bytes in the message data element would have a length of 4. Alength of 0 would denote a blank frame. Because of the 1-bytelimitation, a message data element may not be any longer than 256 bytes.Also, if a frame has been subjected to the replacement of 1Cs with 1B,01, 1Bs with 1B, 02, or 1Ds with 1B, 03, the length describes the lengthof the intended packet before it was encoded to remove the 1Cs, 1Bs or1Ds. This provides another check of the packet's integrity.

The message data element carries the data payload for the frame. Themessage data typically has the same number of bytes as the described inthe length element.

The checksum is the logical addition (ignoring carry overflows) of thelength byte and all of the bytes in the message data element. This maybe used to ensure the integrity of the frame. Also, if a frame has beensubjected to the replacement of 1Cs with 1B, 01, 1Bs with 1B, 02, or 1Dswith 1B, 03, the checksum is performed on the intended packet before itwas encoded to remove the 1Cs, 1Bs or 1Ds. This provides another checkof the packet's integrity.

For messages that originate from the interface unit 14 the first byte ofthe message payload is desired to be 3E hex. Similarly, to comply withthe desired protocol, messages that originate from the sensor unit 12the first byte of the message payload shall be BE hex.

Reference throughout this specification to “one embodiment,” “anembodiment,” “some embodiments,” or similar language means that aparticular feature, structure, or characteristic described in connectionwith the embodiment is included in at least one embodiment of thepresent invention. Thus, appearances of the phrases “in one embodiment,”“in an embodiment,” “in some embodiments” and similar languagethroughout this specification may, but do not necessarily, all refer tothe same embodiment.

While the invention herein disclosed has been described by means ofspecific embodiments, examples and applications thereof, numerousmodifications and variations could be made thereto by those skilled inthe art without departing from the scope of the invention set forth inthe claims.

1. A method for controlling irrigation comprising: generating anindication representing the amount of rain fall at a sensor unit;transmitting a signal comprising at least the indication from the sensorunit to an interface unit, wherein the interface unit is adapted tocause an interruption of programmed watering schedules of an irrigationcontroller and wherein the interface unit is separate from theirrigation controller; receiving the signal at the interface unit;receiving user input relating to the interruption of the programmedwatering schedules of the irrigation controller via a user interfaceintegrated with the interface unit, wherein the user input defines arain interruption threshold; determining, at the interface unit, basedat least on the indication from the signal and the user input, whetherirrigation should be interrupted; and generating an interrupt command tointerrupt irrigation in the event it is determined that the irrigationshould be interrupted.
 2. The method of claim 1, wherein the determiningwhether irrigation should be interrupted step comprises processing thesignal and determining if a relationship exists between a firstthreshold and the indication at the interface unit; and wherein thegenerating the interrupt command step comprises generating the interruptcommand to interrupt irrigation if the relationship exists.
 3. Themethod of claim 1, wherein transmitting the signal step comprises:receiving a request for the indication from the interface unit; andtransmitting the signal comprising at least the indication in responseto the request.
 4. The method of claim 1, further comprising generatingan indication of a temperature at the sensor unit, wherein thetransmitting the signal step further comprises transmitting saidindication of temperature.
 5. The method of claim 4, wherein thedetermining step further comprises determining, based at least on therate of change in temperature whether the irrigation should beinterrupted.
 6. The method of claim 4, wherein the determining stepfurther comprises determining, based at least on the current temperaturewhether the irrigation should be interrupted.
 7. The method of claim 4,further comprising processing the indication to determine whether thereis a change in the temperature, wherein transmitting the signalcomprises transmitting the signal when a change in the temperature isdetected.
 8. The method of claim 4, further comprising processing theindication at the sensor unit, comprising: determining at the sensorunit whether a relationship exists between at least the indication oftemperature and a local threshold; and entering a low temperatureoperational mode at the sensor unit when the relationship exists;wherein the signal comprises at least a low temperature message.
 9. Themethod of claim 8, wherein entering a low temperature operational modecomprises reducing the frequency of generating the indication andtransmitting the signal.
 10. The method of claim 4, wherein determiningwhether irrigation should be interrupted step further comprisesprocessing the signal and determining whether a relationship existsbetween the indication of temperature and a threshold; and wherein thegenerating the interrupt command step further comprises generating theinterrupt command interrupting irrigation if the relationship exists.11. The method of claim 1, wherein the determining step furthercomprises determining, based at least on a rate of rain fall whether theirrigation should be interrupted, the irrigation not in an interruptedstate when the determining is performed.
 12. The method of claim 1,wherein the determining step further comprises determining, based atleast on the total amount of rainfall whether the irrigation should beinterrupted.
 13. The method of claim 1, further comprising processingthe indication to determine whether there is a change in the amount ofrain fall; and wherein transmitting the signal comprises transmittingthe signal when the change in the amount of rain fall is detected. 14.The method of claim 1, wherein the transmitting the signal stepcomprises transmitting the signal wirelessly to the interface unit. 15.The method of claim 1, further comprising sending a request for thesignal from the interface unit to the sensor unit.
 16. The method ofclaim 1, wherein the transmitting the signal step comprises transmittingthe signal periodically.
 17. The method of claim 1, wherein the signalfurther comprises an indication of a signal strength of signals receivedat the sensor unit that were transmitted by the interface unit and abattery strength of the sensor unit.
 18. The method of claim 1, whereinthe transmitting step comprises transmitting the signal over a two-waycommunication link; and wherein the receiving step comprises receivingthe signal over the two-way communication link.
 19. A system forcontrolling irrigation comprising: an interface unit comprising: aninput unit adapted to receive a signal from a sensor unit, the signalcomprising an indication representing an amount of rain fall at thesensor unit; a user interface integrated with the interface unit, theuser interface being adapted to receive user input relating tointerruption of irrigation executed by an irrigation controller, whereinthe user input defines a rain interruption threshold and wherein theinterface unit is separate from the irrigation controller; and acontroller coupled to the input unit adapted to process the signal todetermine based at least on the indication from the signal and the userinput, whether the irrigation executed by the irrigation controllershould be interrupted and to generate an interrupt command to cause theinterruption of the irrigation in the event it is determined that theirrigation should be interrupted; and the sensor unit comprises: asensor adapted to output the indication representing the amount of rainfall; and an output unit adapted to output the signal comprising atleast the indication.
 20. The system of claim 19, wherein the sensorunit further comprises a second input unit adapted to receive therequest from the interface unit and output the signal in response to therequest.